Microhard Systems 00P4 2.4 GHz Spread Spectrum OEM Module User Manual MHX2400MANUA

Microhard Systems Inc 2.4 GHz Spread Spectrum OEM Module MHX2400MANUA

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Operating ManualMHX-24002.4 GHz Spread Spectrum OEM TransceiverRevision 1.11, December 1, 2000Microhard Systems Inc.#110, 1144 - 29th Ave. N.E.Calgary, Alberta T2E 7P1Phone: (403) 248-0028Fax: (403) 248-2762www.microhardcorp.com
ii MHX-2400 Operating ManualMHX-24002.4 GHzSpread-SpectrumEmbedded ModemWARNINGIn order to comply with the FCC/ICadopted RF exposure requirements, thistransmitter system will be installed by themanufacturer's reseller professional.Installation of all antennas must beperformed in a manner that will provide atleast 20 cm clearance from the frontradiating aperture, to any user or memberof the public.This manual contains information of proprietary interest toMicrohard Systems Inc. It has been supplied in confidence topurchasers and users of the MHX-2400, and by accepting thismaterial the recipient agrees that the contents will not be copiedor reproduced, in whole or in part, without prior written consentof Microhard Systems Inc.Microhard Systems Inc. has made every effort to assure that thisdocument is accurate and complete. However, the companyreserves the right to make changes or enhancements to themanual and/or the product described herein at any time andwithout notice. Furthermore, Microhard Systems Inc. assumesno liability resulting from any omissions in this document, orout of the application or use of the device described herein.Microhard Systems’ products are appropriate for home, office,or industrial use, but are not authorized for utilization inapplications where failure could result in damage to property orhuman injury or loss of life.The electronic equipment described in this manual generates,uses, and radiates radio frequency energy. Operation of thisequipment in a residential area may cause radio interference, inwhich case the user, at his own expense, will be required to takewhatever measures necessary to correct the interference.FCC Declaration of ConformityThis device complies with Part 15 of the FCC Rules.Operation is subject to the following two conditions: (1) thisdevice may not cause harmful interference, and (2) thisdevice must accept any interference received includinginterference that may caused undesired operation.Microhard Systems Inc.’s products are warranted against allfailures which occur as a result of defective material orworkmanship within 12 months of purchase by the user. Thiswarranty does not extend to products that, in the opinion ofMicrohard Systems Inc., have been subject to misuse, accidents,lightning strikes, improper installation or application, nor shallit extend to units which have, in Microhard Systems Inc.’sopinion, been opened, tampered with or repaired by anunauthorized facility.Microhard Systems Inc.Leaders in Wireless Telecom#110, 1144 - 29th Ave. N.E.Calgary, Alberta T2E 7P1Phone: (403) 248-0028Fax: (403) 248-2762www.microhardcorp.com© 2000 by Microhard Systems Inc., All Rights Reserved.HyperTerminal is copyrighted by Hilgraeve Inc, and developed for Microsoft.Microsoft and Windows are registered trademarks of Microsoft Corporation.pcANYWHERE and Symantec are registered trademarks of Symantec Corp.All other products mentioned in this document are trademarks or registeredtrademarks of their respective holders.Manual Revision 1.11, December 1, 2000.
Contents1. Introduction1.0 Product Overview .............................................................................................................................................................................. 11.1 Features.............................................................................................................................................................................................. 11.2 About this Manual ............................................................................................................................................................................. 22. Initial Setup and Configuration2.0 Unpacking and Inspection ................................................................................................................................................................. 32.1 Additional Requirements ................................................................................................................................................................... 32.2 Connectors and Indicators.................................................................................................................................................................. 32.3 Configuration..................................................................................................................................................................................... 62.4 Checking the Link............................................................................................................................................................................... 63. Configuration Options3.0 Command Line Interface.................................................................................................................................................................... 93.1 AT Commands................................................................................................................................................................................. 10A - Answer........................................................................................................................................................................................ 10E - Command Echo.......................................................................................................................................................................... 10I - Identification ............................................................................................................................................................................... 10O - Online Mode.............................................................................................................................................................................. 11Q - Quiet Mode................................................................................................................................................................................ 11V - Result Codes Display................................................................................................................................................................. 11W - Connection Result..................................................................................................................................................................... 11Z - Reset Modem and load stored configuration.............................................................................................................................. 11&C - DCD (Data Carrier Detect) ..................................................................................................................................................... 11&D - DTR (Data Terminal Ready)................................................................................................................................................... 11&F - Load Factory default configuration ......................................................................................................................................... 12&K - Handshaking............................................................................................................................................................................ 12&S - DSR (Data Set Ready)............................................................................................................................................................. 12&V - View Configuration ................................................................................................................................................................. 12&E - Framing Error Check................................................................................................................................................................ 12&W - Write Configuration to memory............................................................................................................................................. 12Sxxx? - Read S register value........................................................................................................................................................... 12Sxxx=yyy - Set S register value ....................................................................................................................................................... 123.2 Command Result Codes................................................................................................................................................................... 133.3 S Registers ....................................................................................................................................................................................... 14S Register 2 - Escape Code............................................................................................................................................................... 14S Register 3 - CR Control Code....................................................................................................................................................... 14S Register 4 - Linefeed Control Code .............................................................................................................................................. 14S Register 5 - Backspace Control Code ........................................................................................................................................... 14S Register 101 - Operating Mode..................................................................................................................................................... 15S Register 102 - Serial Baud Rate.................................................................................................................................................... 17S Register 103 - Wireless Link Rate ................................................................................................................................................ 17S Register 104 - Network Address................................................................................................................................................... 18S Register 105 - Unit Address.......................................................................................................................................................... 18S Registers 106 and 206 - Primary and Secondary Hopping Patterns.............................................................................................. 18S Register 107 - Encryption Key...................................................................................................................................................... 20S Register 108 - Output Power Level............................................................................................................................................... 20S Register 109 - Hopping Interval.................................................................................................................................................... 21S Register 110 - Data Format............................................................................................................................................................ 21S Registers 111 and 112 - Packet Minimum and Maximum Size..................................................................................................... 22S Register 116 - Packet Character Timeout ...................................................................................................................................... 22S Registers 113 and 213 - Packet Retransmission/Packet Retry Limit ............................................................................................. 23S Register 115 - Packet Repeat Interval........................................................................................................................................... 24S Register 117 - Modbus Mode ........................................................................................................................................................ 24S Register 120 and 121- RTS/DCD Framing/Timeout ..................................................................................................................... 25S Register 123 - RSSI Reading......................................................................................................................................................... 25A. Modem Command Summary...................................................................................................................................................................... 26B. Serial Interface............................................................................................................................................................................................ 29C. Sample Schematic Diagram........................................................................................................................................................................ 31D. Factory Default Settings.............................................................................................................................................................................. 33EPerformance Tables...................................................................................................................................................................................... 34F. Hopping Tables............................................................................................................................................................................................ 35G. Technical Specifications............................................................................................................................................................................. 36H. Glossary ...................................................................................................................................................................................................... 38
MHX-2400 Operating Manual: Chapter 1 Introduction. 11. Introduction1.0 Product OverviewCongratulations on choosing the MHX-2400 wireless transceiver! Your newMHX-2400 modem is a state-of-the-art, 2.4 GHz frequency-hopping spread-spectrum communications module. When the MHX-2400 module isincorporated into the design of new or existing equipment, terminal devices(DTEs) up to 30 km (or more)1 apart will be capable of establishing high-speed2 communications wirelessly.MHX-2400 modules provide a practical and reliable alternative to usingtraditional analog phone-line modems or “permanent wire” serial cable(RS-232) connections for data communications between asynchronous serialequipment. Moreover, wireless data communications using the MHX-2400module means you will benefit from:ngreater flexibility and freedom to relocate terminal equipment,neliminated requirement for access to wire-based transfer mediasuch as telephone lines,nthe ability to communicate through walls, floors, and manyother obstacles.While the MHX-2400 module is compact in its design, it delivers power andconvenience and offers quality and dependability. The MHX-2400 module’sversatility makes it the ideal solution for applications ranging from office-productivity to industrial data control and acquisition.While a pair of MHX-2400 modules can link two terminal devices (“point-to-point” operation), multiple MHX-2400 modules can be used together tocreate a network of various topologies, including “point-to-multipoint” and“repeater” operation. Multiple independent networks can operateconcurrently, so it is possible for unrelated communications operations totake place in the same or a nearby area without sacrificing privacy,functionality, or reliability.1.1 FeaturesKey features of the MHX-2400 module include:ntransmission within a public, license-exempt band of the radiospectrum3 – this means that it can be used without access fees(such as those incurred by cellular airtime);na serial I/O data port (TTL levels) with handshaking andhardware flow control, allowing the MHX-2400 module tointerface directly to any microprocessor with an asynchronousserial interface. 1Ideal conditions with clear line-of-sight communications, using high-gain antennas.2Up to 115,200 bits per second (bps).3902-928 MHz, which is license-free within North America; may need to be factory-configureddifferently for some countries.
2MHX-2400 Operating Manual: Chapter 1 Introductionn49 sets of user-selectable pseudo-random hopping patterns,intelligently designed to offer the possibility of separatelyoperating multiple networks while providing security, reliabilityand high tolerance to interference;nencryption key with 65536 user-selectable values to maximizesecurity and privacy of communications;nbuilt-in CRC-16 error detection and auto re-transmit to provide100% accuracy and reliability of data;nease of installation and use – the MHX-2400 module uses asubset of standard AT style commands, very similar to thoseused by traditional telephone line modems.While the typical application for the MHX-2400 is to provide a short- to mid-range wireless communications link between DTEs, it can be adapted toalmost any situation where an asynchronous serial interface is used and dataintercommunication is required.1.2 About this ManualThis manual has been provided as a guide and reference for installing andusing MHX-2400 wireless modem modules. The manual containsinstructions, suggestions, and information which will help you set up andachieve optimal performance from your equipment using the MHX-2400module.It is assumed that users of the MHX-2400 module have either systemintegration or system design experience. Chapter 2 details the requirementsand connections of the MHX-2400 module. Chapter 3 describes the ATcommand register setup and configuration. The Appendices, including theGlossary of Terms, are provided as informational references which you mayfind useful throughout the use of this manual as well as during the operationof the wireless modem.Throughout the manual, you will encounter not only illustrations that furtherelaborate on the accompanying text, but also several symbols which youshould be attentive to:Caution or Warning: Usually advises against some action which couldresult in undesired or detrimental consequences.Point to Remember: Highlights a key feature, point, or step which is worthnoting, Keeping these in mind will make using the MHX-2400 moreuseful or easier to use.Tip: An idea or suggestion is provided to improve efficiency or to makesomething more useful.With that in mind, enjoy extending the boundaries of your communicationswith the MHX-2400 module.
MHX-2400 Operating Manual: Chapter 2 Initial Setup and Configuration 32. Initial Setup and Configuration2.0 Unpacking and InspectionThe following items should be found in the shipping carton. Inspect thecontents for any shipping damage. Report damages or shortages to thedistributor from which the unit was purchased. Keep all packing materials inthe event that transportation is required in the future.Package contents (normal distribution):1MHX-2400 Wireless Modem module 12Operating Manual (this document) 12.1 Additional RequirementsSince the MHX-2400 module is a unique product in a class of its own, it willcommunicate only with another MHX-2400 module which has beencompatibly configured. Thus, at least two MHX-2400 modules will berequired to establish a wireless communications link.Additionally, the following requirements should be taken into considerationwhen preparing to incorporate the MHX-2400 module in new or existingdesigns.nSmall footprint for the MHX-2400 module (e.g., 2.1” W x 3.5” Lx 0.8” H) on the OEM PCB.nSerial port and control signals from the host microprocessor.See sample application schematics in Appendix C.n+5 Vdc supply from the host OEM electronics.nAn external antenna (customer supplied).2.2 Connectors and IndicatorsThe MHX-2400 module connects to the host equipment by two single rowheader strips on the underside of the unit. This enables the MHX-2400module to be directly soldered or socketed onto the host equipmentmanufacturer’s PCB. The pinout for the module is given in Figure 1.
4MHX-2400 Operating Manual: Chapter 2 Initial Setup and ConfigurationIMPORTANT:For best performance, it isstrongly recommended to usea separate, linearly regulatedsupply for Vcc Radio. Donot directly feed a switchingpower supply into VccRadio.For OEM design simplicity,connect both the radio andlogic Vcc connectionstogether.Caution: Using any other powersupply which does not provide theproper voltage or current coulddamage the MHX-2400 module.120Top ViewAntenna Connector2140Vcc RadioVcc RadioVcc LogicN/C/CONFIG/RESETGNDGNDGNDN/CTx Mode LEDRSSI LED 3RSSI LED 2RSSI LED 1CTSRTSDSRN/CDTRTxDRxDDCDVcc LogicVcc LogicVcc LogicVcc LogicGNDGNDGNDGNDN/CN/CN/CN/CN/CN/CN/CN/CN/CRx Mode LEDFigure 1 - Pinout DiagramThe interface connectors and indicator lights are summarized below:Vcc Radio - These pins supply power for the MHX-2400’s radio circuitry. Bestperformance is achieved by providing linearly regulated voltage to thesepins. It is essential to keep this supply rail as clean as possible -preferrably by not directly feeding a switching power supply into VccRadio. In addition, it is recommended that Vcc Radio be regulated asclose to 5.5V as possible (without exceeding 5.5V). Running from a 5Vregulator will decrease the transmitted power by roughly 1dB. The linearregulator must be rated for at least 800 mAVcc Logic - These pins supply power for the MHX-2400’s digital circuitry. It isrecommended you use a linear regulator to feed Vcc Logic. Currentconsumption in the logic circuitry is typically 100 mA. The regulatorshould be rated for at least 200 mA. To simplify the OEM design, theRadio Vcc can be connected to the Logic Vcc.GND - Ground return pins for both Radio and Logic circuitry/RESET - This momentary active low input signal (100 ms typical) resets theMHX-2400./CONFIG - Leave this pin unconnected. Do NOT ground.Receive Signal Strength Indicator (RSSI) - These active high TTL outputs aredesigned to drive LED’s. As the signal strength increases, the number ofactive RSSI lines increases, starting with RSSI1. When configured as aRepeater, the module does not indicate RSSI. The LED’s perform a“scanning” function, blinking on and off in sequence when a Slave orRepeater modem is searching for synchronization. The current sourcingcapability of these lines is 20 mA.
MHX-2400 Operating Manual: Chapter 2 Initial Setup and Configuration 5Data Port (DCE) - Pins 21 through 28 inclusive. This port is used to interfacethe MHX-2400 module to a DTE device and operates at 2400 to 115,200bps. The levels are active low 5V logic levels, and include (SeeAppendix B for a complete description):Pin No. Name Description I/O21 DCD Data Carrier Detect O22 RxD Receive Data O23 TxD Transmit Data I24 DTR Data Terminal Ready I25 NC No Connect26 DSR Data Set Ready O27 RTS Request to Send I28 CTS Clear to Send ORX Indicator - This active high output indicates the modem is receiving datapackets with correct CRC, and is designed to drive a LED. When the unitis configured as a Slave, this LED will typically be on solid under goodoperating conditions.TX Indicator - This active high output is designed to drive a LED, and indicatesthe modem is transmitting.Antenna Connector - The MHX-2400 uses an end launch SMA RFconnector. Microhard Systems can provide the cabling from themodule to the appropriate antenna connector. A suitable antenna mustbe used to ensure adequate performance of the MHX-2400 module.N/C - These pins are reserved for future use. Do not connect to these pins.
6MHX-2400 Operating Manual: Chapter 2 Initial Setup and ConfigurationMSNetwork 1MSRMSRNetwork 2MSSSNetwork 3MRSSSNetwork 4MRSRSNetwork 5Figure 2 - Sample NetworkTopologies. Virtually anyCombination of Slaves andRepeaters May be Used.2.3 ConfigurationPrior to establishing a wireless link, each MHX-2400 module participating inthe link must be correctly configured for compatibility and for the desiredmode of operation.Network topologies consisting of a single Master and virtually anycombination of Slaves and Repeaters may be deployed. The functionality ofany particular MHX-2400 can be configured as follows:nMaster Point-to-Point: The module is configured tocommunicate with a single Slave, either directly, or through oneor more Repeaters.nMaster Point-to-Multipoint: The module is configured tocommunicate with one or more Slaves and/or Repeaters.nSlave: The module is configured to communicate with oneparticular Repeater or Master.nRepeater: The module is configured to pass information fromeither a Master or another Repeater onto subsequent Repeatersand/or Slaves and vice versa. The Repeater also acts as a Slavein the sense that, like a Slave, it passes information to/from itsserial port.All units within a network must be assigned a common Network Address;thus enabling multiple networks to co-exist in the same vicinity withoutunwanted crosstalk between modules. Examples of different networktopologies are shown in Figure 2. Network 1 shows Point-to-Pointcommunication between a Master and Slave. Network 2 makes use of aRepeater to communicate with the Slave. Network 3 illustrates a simplePoint-to-Multipoint network with no Repeaters. Networks 4 and 5 givesexamples of Point-to-Multipoint networks consisting of both Repeaters andSlaves. There is effectively no restriction to the number of Repeaters andSlaves that can be added to a network. As seen in Network 4, a Master cancommunicate directly with both Slaves and Repeaters. The MHX-2400 hasbeen designed to allow for additional Repeaters and Slaves to be added to anexisting network without having to reconfigure any units already in thenetwork. This saves a tremendous amount of time when deploying additionalunits in the field.2.3.1 Quick Start ApproachThe MHX-2400 is equipped with four standard factory default settings.Instead of manually configuring each individual operating parameter, a globalcommand may be used to quickly configure the modem for a particular typeof operation. For example, to quickly implement Network 1, Factory default1 would be applied to the Master, and Factory default 2 would be applied tothe Slave. To quickly set up Network 2, apply Factory 1 to the Master,Factory 3 to the Repeater, and Factory 4 to the Slave. These defaults will getyou started and only ensure that a link can be established, but do notnecessarily provide the best performance. Optimization of thecommunications link is discussed in later sections.
MHX-2400 Operating Manual: Chapter 2 Initial Setup and Configuration 7Warning: Using an antenna thatis inappropriate for use with theMHX-2400 module could result inundesired performance, and maydamage the unit. It is the user’sresponsibility to ensure theantenna has adequate lightningprotection.How to Set Up A Simple NetworkThe MHX-2400 will always be in one of two states:nData Mode – When in this state, the modem is listening and talkingto other modems in the network (the modem is online).nCommand Mode – When in this state, the modem is awaiting “ATCommands” from the serial port. These commands are used toconfigure all operating parameters of the modem. When in thisstate, the modem is “offline”.To implement the very basic network illustrated in Figure 2, Network 1,nPlug the modem into the development board and connect a straight-through serial cable between the development board and theterminal (e.g., your PC)nConnect an antenna cable and antenna to the module.nConfigure the unit to Factory Setting 1 by typing AT&F1 <return>.This puts the unit into Master Point-to-Multipoint mode.nStore these settings to memory by typing AT&W <return>.nPut the modem into Data Mode by typing ATA <return>. There areother ways to enter Data Mode, which are discussed in Chapter 3.nPerform the above steps for the second unit, using the commandAT&F2 instead of AT&F1. This will configure the second unit as aSlave.The units should now be communicating. Remember, the parameters definedby AT&F1 and AT&F2 will likely not be the most ideal for your application,but will quickly allow you to test the units. A complete summary of thesettings defined by AT&F1,2,3 and 4 can be found in Appendix D. FactoryDefault Settings.Settings are not immediately stored in non-volatile memory, therefore, thecommand &W is issued to store the current configuration into non-volatilememory. Settings are retained even after powering down. All user selectableparameters for the MHX-2400 are described in detail in Chapter 3:Configuration Options.2.4 Checking the LinkTo check if the units are communicating, observe the LED indicators on thedevelopment board. If the link is good, up to three RSSI outputs on the Slavemodem should be active; and if the link is absent (due to a fault at one end oranother, such as misconfiguration), the outputs will be in either “scanningmode” or inactive.Characters typed at the Master terminal should appear at the Slave’s terminal,and vice versa. Also, verify that the RX LED blinks as packets of data arereceived at the Master modem. As data is sent from Slave to Master, the RXindicator should blink on as correct packets of data are received. It isrecommended that if MHX-2400 modules will be deployed in a field wherelarge distances separate the units, the modems should be configured andtested in close proximity (e.g., in the same room) first to ensure a good linkcan be established and settings are correct. This will facilitatetroubleshooting, should problems arise.
8MHX-2400 Operating Manual: Chapter 3 Configuration Options3. Configuration OptionsThe escape sequence will notbe accepted unless both theMHX-2400 and the terminalare set to the same baud rateRefer to Appendix A (page19) for a summary of themodem commandsConfiguration options arenot stored in non-volatilememory until the WRITEcommand (&W) is executed3.0 Command Line InterfaceThe MHX-2400 modem can be easily configured to meet a wide range ofneeds and applications. You can have your modem perform a variety offunctions by sending it instructions (in the form of commands). Sending acommand overrides the modem’s operating characteristics.Your modem must be in Command Mode for it to execute a command. Ifyou send characters when the modem is in Data Mode, the modem transmitsthe characters over the air.Depending on its settings, the modem will either power up in CommandMode or Data Mode. Normally, when first received from the factory, theunit will power up in Command Mode.You can place the modem into Data Mode either by1. Issuing the answer command2. Issuing the online commandYou can place the modem into Command Mode either by1. Sending the escape sequence2. Toggling the DTR line (depending on the &D parameter see pg 11).To enter a command line and have your modem execute it, use the followingprocedure:1. With your modem in the Command Mode, type AT. These characters,known as the attention characters, must be typed at the beginning ofeach command line.2. Type the command(s). Include any parameters required by thecommand. To make the command line more readable, you can insert asmany spaces as desired. The command line holds up to 16 characters,not including the AT prefix.3. Press the ENTER key. Your modem executes the command line andsends you a word response (usually OK).For example, to set the Operating Mode S101 register to Master Point-to-Multipoint mode, enter the following command line; AT S101 = 1 <return>.To display what a register is currently set to, enter the following commandline; AT Sxxx? <return>. The modem will output the value of the register.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 9Note: If you want to send more than one command line, wait for a responsebefore entering the AT prefix at the start of the next command line.To re-execute the previous command, enter A/. The modem will executethe previous command line.When in Command Mode, the modem “autobauds”, meaning that it willautomatically adjust to the baud rate of the terminal. You may change theterminal baud rate while in Command Mode without losing communicationwith the modem.For the AT command protocol, an escape sequence consists of threeconsecutive escape codes preceded and followed by at least 1 second ofinactivity. Typically, the ‘+’ character is used as the escape code.+++ preceded and followed by 1 second of inactivityNote that the terminal must be configured to the same baud rate as themodem in order for the mode to recognize the escape sequence. Themodem is unable to “autobaud” while in Data Mode.3.1 AT CommandsSeveral AT Commands are supported by the MHX-2400 module. Thefollowing is a short description of all available commands. ‘*’ denotesstandard factory settings. All of the following commands must be precededby “AT”AAnswerThe A command causes the modem to attempt to connect with anotherremote modem (Type ATA <return>).ECommand EchoYour modem is preset to return (or echo) commands to the hostmicroprocessor when in Command Mode.E0 No Command Echo*E1 Command EchoIIdentificationThe I command returns various modem information settings.I1 Product Code (MHX-2400)I2 Issue ROM Check (OK or ERROR)I3 Product Identification (Firmware Version)I4 Firmware DateI5 Firmware CopyrightI6 Firmware TimeI7 Serial Number
10 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsOOn-line ModeThe O command attempts to put the modem online and communicate with aremote modem.QQuiet ModeYour modem is preset to send responses when it executes commands, andthere after to keep the host informed of its status.*Q0 Enable modem responsesQ1 Disable modem responsesVResult Codes displayYour modem can either display result codes as words or numbers.V0 Display Result Codes as numbers*V1 Display Result Codes as wordsWConnection ResultThe W command returns your modem to the Data Mode from the CommandMode*W0 Reports computer (DTE) baud rate as CONNECT xxxxW1 Reports computer (DTE) rate and wireless rate between modems as CARRIER xxxx.W2 Reports modem (DCE) baud rate as CONNECT xxxxZReset and load stored configurationThe Z command resets the modem and loads the stored configuration.&C DCD (Data Carrier Detect)The &C command controls the modem’s DCD output signal to the hostmicroprocessor. This command determines when the DCD is active.&C0 DCD is always ON*&C1 DCD on when modems are synchronized. DCD is alwayson when unit is configured as Master.&C2 DCD used for output data framing and Modbus mode.See page 25 for details.&D DTR (Data Terminal Ready)The &D command controls what action the modem performs when the DTRinput line is toggled. The DTR input is controlled by the hostmicroprocessor.*&D0 DTR line is ignored&D1 Not Supported&D2 DTR disconnects and switches to Command Mode&D3 DTR disconnects and resets modem. Modem will remainin this state until DTR again goes active.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 11&F1 &F2Master Slave&F1 &F4&F3Master Repeater Slave&F Load Factory Default ConfigurationThe &F command resets the modem and loads the default factoryconfiguration.&F1 Master Point-to-Multipoint. Designed to communicatewith modems configured as &F2 or &F3.&F2 Slave. Designed to communicate with another modemconfigured as &F1.&F3 Repeater. Designed to communicate with modemsconfigured as &F1 and &F4.&F4 Slave working with factory default Repeater and factorydefault Master. Communicates directly with Repeaterconfigured as &F3.&K HandshakingThe &K command controls the handshaking between the modem and hostmicroprocessor.&K0 Disable handshaking&K2 RTS/CTS input data framing. See page 25 for details.*&K3 Enable hardware handshaking (RTS/CTS)&S DSR (Data Set Ready)The &S command controls the DSR line for the modem, and determineswhen it is active&S0 DSR is always ON*&S1 DSR is ON in Data Mode, OFF in Command Mode&V View ConfigurationThe &V command displays the current (DTE) baud rate, and all setablemodem parameters including S register values.&E Framing Error CheckThis command enables or disables Framing Error Check. When enabled,the modem looks for the stop bit. If the stop bit is absent, the byte is thrownout. When enabled, the modem also does a parity check. Note that the dataformat (number of data bits, parity type, and number of stop bits) is definedby S register 110.*&E0 Disable Framing Error Check&E1 Enable Framing Error Check&W Write Configuration to MemoryThe &W command stores the active configuration into the modem’s non-volatile memory.Sxxx? Read S register valueThis command causes the modem to display the current setting of S registerxxx.Sxxx=yyy Set S register value (see section 3.3 S-Registers)This command sets the specified S register to a value specified by yyy.
12 MHX-2400 Operating Manual: Chapter 3 Configuration Options3.2 Command Result CodesThe MHX-2400 module can either display the results of a command aseither text strings or numerical data. The following chart shows resultingtext string and corresponding numeric result.0OK3NO CARRIER4ERROR7CONNECT 24008CONNECT 36009CONNECT 480010 CONNECT 720012 CONNECT 960013 CONNECT 1440014 CONNECT 1920015 CONNECT 2880017 CONNECT 3840018 CONNECT 5760033 CONNECT 11520062 CARRIER 4500064 CARRIER 20000
MHX-2400 Operating Manual: Chapter 3 Configuration Options 13S Registers 2 through 5cannot be stored to non-volatile memory.3.3 S RegistersS Register 0 - Auto AnswerIf this register is set to zero, the modem will power up in command mode. Ifthis register is non-zero, the modem will power up in data mode.S Register 2 - Escape CodeThis register contains the ASCII value of the escape character.The default value (decimal 43) is equivalent to the ASCII character ‘+’.Values greater than 127 disable the escape feature and prevent you fromreturning to the Command Mode. This register cannot be stored to non-volatile memory. If the modem is reset, or powered down, the default valueis restored.Default is ‘+’ (decimal 43).S Register 3 - CR Control CodeThis register contains the ASCII value of the carriage return character.This is the character that is used to end the command line and is also thecharacter that appears after the modem sends a response. This registercannot be stored to non-volatile memory. If the modem is reset, or powereddown, the default value is restored.Default is ‘CR’ (decimal 13).S Register 4 - Linefeed Control CodeRegister S4 sets the ASCII value of the linefeed character.The modem sends the linefeed character after sending a carriage returncharacter when sending text responses. This register cannot be stored tonon-volatile memory. If the modem is reset, or powered down, the defaultvalue is restored.Default is ‘LF’ (decimal 10).S Register 5 - Backspace Control CodeRegister S5 sets the ASCII value of the backspace character.This character is both the character created by entering BACKSPACE andthe character echoed to move the cursor to the left. This register cannot bestored to non-volatile memory. If the modem is reset, or powered down, thedefault value is restored.Default is ‘BS’ (decimal 8).
14 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsOnly one Master can existfor each network.S Register 101 - Operating ModeThe Operating Mode (register S101) partly defines the “personality” of theMHX-2400 module. Allowable settings for this register are 1 through 4 asfollows:.• S101=1 Master Point to Multipoint• S101=2 Master Point to Point• S101=3 Slave• S101=4 RepeaterThe default for this register depends on which factory default is selected asshown below:• Default for Factory Setting &F1 is 1 (Master Point-to-Multipoint)• Default for Factory Setting &F2 is 3 (Slave)• Default for Factory Setting &F3 is 4 (Repeater)• Default for Factory Setting &F4 is 3 (Slave)1)Master - Point to Multipoint. In any given network, thereis always only one Master. All other units should be configured as eitherSlaves or Repeaters. When defined as a Point-to-Multipoint Master, themodem broadcasts data to all Slaves and Repeaters in the network, and isalso the ultimate destination for data transmitted by all Slaves andRepeaters. In addition, the Master defines the following network parametersto be utilized by all other modems in the network (See the appropriatesections for a complete description of these parameters):nMaximum Packet Size (S112)nMinimum Packet Size (S111)nWireless Link Rate (S103)nHop Interval (S109)2)Master - Point to Point. This mode of operation is identicalto Master Point-to-Multipoint, with the exception that the Master onlybroadcasts to one particular Slave or Repeater. The modem with whichcommunication occurs is defined by the Unit Address (S105). For example,if a Slave has been assigned Unit Address 100, and the Master wishes tocommunicate with that Slave, the Master must also be assigned a UnitAddress of 100. If there are Repeaters in the network, they will pass thepacket through to the Slave, and vice versa. Because Repeaters also haveSlave functionality (i.e., a Repeater can be connected to a terminal), theMaster can choose to communicate solely with a Repeater. This would beaccomplished by assigning the same Unit Address to both the Master andthe Repeater.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 15PHP=1 PHP=2PHP=1SHP=2MasterRepeaterSlaveNetwork 50Hop Pattern 1Hop Pattern 2Figure 3 - RepeaterOperationMaster RepeaterSlaveRepeaterSlavePHP=1 PHP=1SHP=2PHP=2PHP=2SHP=3 PHP=3Hop-Pattern 1Hop Pattern 2Hop Pattern 3Figure 4 - A NetworkUtilizing Three HoppingPatternsIf there is no DTE connectedto the Repeater, turn offhandshaking (&K0) and setthe baud rate to 115K.3)Slave. Up to 65534 Slaves may exist in a network, all of whichcommunicate with the common Master (either directly or via Repeater(s)).Slaves cannot directly communicate with other Slaves, nor can theyacknowledge packets of data sent by the Master. Clearly this would causeconflicts when there are multiple Slaves. The Master does, however, sendacknowledgements to all messages it receives from Slaves. The Masterinitiates communications by sending a broadcast message to all Slaves. AllSlaves are free to respond in a “Slotted ALOHA” fashion, meaning that eachSlave can choose one of several windows in which to transmit. If therehappens to be two Slaves attempting to talk at the same time, the Mastermay not receive the data, and the Slaves therefore would not get anacknowledgement. At this point, the Slaves would attempt to get theinformation through at random time intervals, thus attempting to avoid anymore conflicts. Special parameters which control the Slave’s responsecharacteristics can be modified with S Registers S115 and S213.4) Repeater. A more precise title would be Repeater/Slave, because aRepeater also has much of the same functionality as a Slave. A terminal canbe connected at the Repeater location and communicate with the Masterterminal. There is no restriction to the number of Repeaters in a network,allowing for communication over virtually limitless distances. The presenceof one Repeater in a network automatically degrades system throughput byhalf. Additional Repeaters, regardless of the quantity, do not diminishsystem throughput any further. To understand Repeater operation, considerthe module as belonging to two hopping patterns at the same time: ThePrimary Hopping Pattern and the Secondary Hopping Pattern. In Figure 3,the Master belongs to Hopping Pattern 1, and communicates with theRepeater on this hopping pattern. The Slave belongs to Hopping Pattern 2,and communicates with the Repeater on this hopping pattern. The wholesystem belongs to Network 50 (i.e., all units must be assigned the sameNetwork Address (S104), which in this case was selected to be 50. Notethat Slaves and Master only communicate on their respective PrimaryHopping Pattern. Repeaters communicate on the Primary Hopping Patternwhen communicating with the Master (or with another Repeater betweenitself and the Master). Repeaters communicate on their Secondary HoppingPattern when communicating with Slaves (or with another Repeater betweenitself and the Slaves). Figure 4 shows another example.If the Repeater is not also being used as a Slave (there is no DTE connectedto the serial port), it is recommended that the Repeater’s baud rate be set to115K, and that handshaking be disabled (&K0). This will help ensure asmooth flow of data through the network.
16 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsThe Master determines theWireless Link Rate. Thissetting on all other modemsis ignored..S Register 102 - Serial Baud RateThe Serial Baud Rate is the current speed that the modem is using tocommunicate with the DTE. When the AT command prefix is issued, themodem performs an ‘autobaud’ operation and determines what the currentDTE baud rate is set to. The S register value returns the current setting ofthe DTE baud rate.The possible values are:* 1 1152002 576003 384004 288005 192006 144007 96008 72009 480010 360011 2400It is generally advisable to choose the highest rate that your terminalequipment will handle to maximize performance, unless a limitation on theavailable bandwidth is desired. If the DTE is a personal computer, the portcan usually be used reliably at 115200. It is not possible to write values tothis register, since the instant another AT command is issued, the registerwill revert to the current baud rate. Therefore, it is advisable to operate inCommand Mode at the desired baud rate for Data Mode.S Register 103 - Wireless Link RateThe Wireless Link Rate is the speed and optimization method for whichmodems will communicate over the RF link. It is only necessary to set thisparameter on the Master unit. Units configured as Repeaters and Slaves willignore this setting, and adjust automatically to the rate of the Master.The allowable settings are:2Fast without Forward Error Correction*4Fast with Forward Error CorrectionDepending on the application requirements, each mode will providedifferent throughput and performance. Appendix E. Performance Tablesgive some indication of the performance to be expected in each mode.In general, Forward Error Correction (FEC) reduces throughput, but in someenvironments will actually increase throughput. FEC can reduce the numberof bad data packets, and hence reduce the need to retransmit.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 17Select a Network Addressand assign it to all unitswhich will be included in thenetwork.Use the same Unit Addresson both units for point-to-point mode. In multipointmode, set each Slave andRepeater to a different UnitAddress.Valid Unit Addresses are 1to 65535.S Register 104 - Network AddressThe Network Address defines the membership to which individual units canbe a part of. By establishing a network under a common Network Address,the network can be isolated from any other concurrently operating network.As well, the Network Address provides a measure of privacy and security.Only those units which are members of the network will participate in thecommunications interchange. Valid values for the Network Address rangefrom 0 to 65535, inclusive.To enhance privacy and reliability of communications where multiplenetworks may operate concurrently in close proximity, it is suggested that anatypical value be chosen – perhaps something meaningful yet not easilyselected by chance or coincidence.Default is 1.S Register 105 - Unit AddressIn point-to-point operation, the Unit Address on both the Master and Slave(or Repeater) units must be the same. In a multipoint system, the UnitAddress uniquely identifies each Slave and Repeater from one another.Each unit in a multipoint system must have a unique Unit Address rangingfrom 1 to 65535. Do not use 0 as a Unit Address, and do not use a UnitAddress more than once within the same Network. This is required becausethe Master must be able to acknowledge each unit individually, based on theUnit Address.S Register 106 - Primary Hopping PatternS Register 206 - Secondary Hopping PatternSince the MHX-2400 is a frequency-hopping modem, the carrier frequencychanges periodically according to one of 49 pseudo-random patterns,defined by the Primary and Secondary Hopping Patterns. Valid entries foreach are 0 through 50.The concept of Primary and Secondary Hopping Patterns was introduced inthe discussion of S Register 101 (Operating Mode).Using the designations M[a,] Rx[a,b] and Sx[a] where:- M indicates Master;- R indicates Repeater;- S indicates Slave;- x is the Unit Address;- a is the primary hopping pattern; and,- b is the secondary hopping pattern;
18 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsMaster SlaveMaster Repeater SlaveMaster Repeater1 Repeater2 SlaveSlaves and Masters do notuse Secondary HoppingPatternsRemember to assign aunique Unit Address (1 to65535) to each unit in thesystemthe following diagrams illustrate the methodology for deploying simple tocomplicated networks:M[1] ←→ S1[1]M[1] ←→ R1[1,2] ←→ S2[2]M[1] ←→ R1[1,2] ←→ R2[2,3] ←→ S3[3]M[1] ←→ R1[1,2] ←→ R2[2,3] ←→ R3[3,4] ←→ S4[4]It is reasonable to consider a Repeater as being both a Slave and a Master,alternating between Primary and Secondary Hopping Patterns as the unitchanges channel. Consider R1 in the illustration below. Whencommunicating with the Master, R1 is acting like a Slave on PrimaryHopping Pattern 1. When communicating with R2 and S4, R1 is acting likea Master on Secondary Hopping Pattern 2. If multiple Repeaters are used,they should have different Secondary Hopping Patterns:←→ R1[1,2] ←→ R2[2,5] ←→ S3[5]M[1] ←→ S4[2]←→ R5[1,3] ←→ R6[3,6] ←→ S7[6]←→ R8[1,4] ←→ S9[4]Note that all units have a unique Unit Address.Networks of any complexity can be created by linking multiple Repeatersand Slaves:←→ R1[1,2] ←→ S2[2]←→ S3[2]←→ ←→ R5[3,6] ←→ S6[6]M[1] R4[1,3] ←→ S7[6]←→ R8[3,7] ←→ R9[7,8] ←→ S10[8]←→ S11[1]←→ S12[1]With a limitation of 51 hopping patterns, one might suspect that there is alimitation to the number of repeaters in a system. However, if the units arefar enough away from one another, hopping patterns may be reused indifferent sections of the network, without causing interference.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 19All units within a networkmust use the sameencryption key.S Register 107 - Encryption KeyThe Encryption Key provides a measure of security and privacy ofcommunications by rendering the transmitted data useless without thecorrect key on the receiver. Valid Encryption Keys range from 0 to 65535.Keep in mind that all units within the network must use the same key forcommunications to succeed.S Register 108 - Output Power LevelThe Output Power Level determines at what power the MHX-2400transmits. The super-sensitive MHX-2400 can operate with very low powerlevels, so it is recommended that the lowest power necessary is used; usingexcessive power contributes to unnecessary “RF pollution”.The allowable settings are:010 mW 4500 mW150 mW 5750 mW*2 100 mW 61 W3250 mWIdeally, you should test the communications performance between unitsstarting from a low power level and working upward until the RSSI issufficiently high and a reliable link is established. Although the conditionswill vary widely between applications, typical uses for some of the settingsare described below:Power Use10 mW For in-building use, typically provides a link up to 300 feet on thesame floor or up/down a level. Outdoors, distances of 10 km can beachieved if high-gain (directional) antennas are placed high aboveground level and are in direct line-of-sight.50 mW 200-500 ft indoors, 8-15 km* outdoors.100 mW 400-800 ft indoors, 15-25 km* outdoors.1000 mW(1 W)Typically provides communications up to a distance of 1000 feet ormore in-building on the same floor or up/down a few levels,depending on building construction (wood, concrete, steel, etc.). Inideal line-of-sight conditions, up to 30 km* or more can beachieved. Note that only an antenna with a gain of no more than 6dBi may be used. Any higher is a violation of FCC rules. SeeIMPORTANT warning below.* These outdoor distances assume antennas are mounted at least 100 ftabove ground level
20 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsThe hopping interval iscontrolled by the master.The slave and repeater unitswill use the hopping intervalsetting from the master.IMPORTANT:FCC Regulations allow up to 36 dBi effective radiated power (ERP).Therefore, the sum of the transmitted power (in dBm), the cabling lossand the antenna gain cannot exceed 36 dBi.1 mW = 0 dBm10 mW = 10 dBm100 mW = 20 dBm1000 mW = 30 dBmFor example, when transmitting 1 Watt (30 dBm), with cabling losses of2 dB, the antenna gain cannot exceed 36 - 30 + 2 = 8 dBi. If an antennawith a gain higher than 8 dBi were to be used, the power setting mustbe adjusted appropriately. Violation of FCC regulations can result insevere fines.S Register 109 - Hopping IntervalThis option determines the frequency at which the modems change channel.Note that the Master controls this parameter for the entire network. Thissetting is ignored in units configured as Slaves or Repeaters.The allowable settings are:18 msec212 msec316 msec420 msec530 msec645 msec780 msec*8 120 msecSee Appendix E for optimal Hopping Interval settings in relation to packetsize and link rate.S Register 110 - Data FormatThis register determines the format of the data on the serial port. Allowablesettings are:*1 8 bits, No Parity, 1 Stop28 bits, No Parity, 2 Stop38 bits, Even Parity, 1 Stop48 bits, Odd Parity, 1 Stop57 bits, No Parity, 1 Stop67 bits, No Parity, 2 Stop77 bits, Even Parity, 1 Stop87 bits, Odd Parity, 1 Stop97 bits, Even Parity, 2 Stop10 7 bits, Odd Parity, 2 Stop11 9 bits, No Parity, 1 Stop
MHX-2400 Operating Manual: Chapter 3 Configuration Options 21The Minimum andMaximum Packet Size iscontrolled by the Master.The Slave and Repeater unitswill use the Minimum andMaximum Packet Sizesetting from the Master.S Register 111 - Packet Minimum SizeS Register 112 - Packet Maximum SizeS Register 116 - Packet Character TimeoutThese settings determine the conditions under which the modem willtransmit accumulated data over the air.S Register 111 - Minimum SizeValid entries for this register are 1 to 255 bytes, which defines the minimumnumber of bytes to receive from the DTE before encapsulating them in apacket and transmitting over the air.Note that the minimum packet size for all modems in the network isdetermined by the Master only. This setting is ignored in all Slave andRepeater modems. The default is 1 byte.S Register 112 - Maximum SizeThis setting has a range of 2 to 255, and defines the maximum number ofbytes from the DTE which should be encapsulated in a packet. This valueshould be greater than the minimum packet size, but not smaller than isnecessary for reliable communications. If the wireless link is consistentlygood and solid, a maximum size of 255 will yield the best throughput(depending on the higher level protocols of the connected equipment).However, if the link is poor (e.g., experiencing excessive interference) anddata is frequently retransmitted, the maximum packet size should bereduced. This decreases the probability of errors within packets, andreduces the amount of traffic in the event that retransmissions are required.Note that the maximum packet size for all modems in the network isdetermined by the Master only. This setting is ignored in all Slave andRepeater modems. The default is 255 bytes.S Register 116 - Packet Character TimeoutThis register has valid entries of 0 to 254 milliseconds. The PacketCharacter Timeout timer looks for gaps in the data being received from theDTE. The timer is only activated after the Minimum Packet Size has beenaccumulated in the modem. After which, if the timer detects a gap in thedata exceeding the Packet Character Timeout value, the modem willtransmit the data.The MHX-2400 will accumulate data in its buffers from the DTE until oneof the following requirements is met (whichever occurs first):• The Maximum Packet Size (in bytes) has been accumulated;• The Minimum Packet Size has been accumulated AND the PacketCharacter Timeout interval has elapsed.The default for the Packet Character Timeout is 9 ms. If set to 0 ms, theunit will buffer exactly the minimum packet size before transmitting.
22 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsS Register 113 - Packet RetransmissionsThis register applies to both Master and Repeater operation. It does notapply to Slave operation. The Master will retransmit each data packetexactly the number of times defined by the Packet Retransmissionsparameter. The Master retransmits once at the beginning of each hoppinginterval until the limit is reached. This parameter is not necessary in Slaveunits since all Slaves receive acknowledgement from the Master. Asdiscussed previously, the Repeater effectively behaves as both a Master anda Slave. When the Repeater is tuned to its Secondary Hopping Pattern(acting as a Master), the Packet Retransmissions Parameter comes into play.The Repeater will re-send packets of data on to Slaves or other Repeatersexactly the number of times defined by the Packet Retransmissionsparameter.Recipients of the packet will discard any duplicates The valid settings forthis parameter are 0 to 255 retransmissions. The default is 2.S Register 213 - Packet Retry LimitPacket Retry Limit is analogous to Packet Retransmissions, but specificallyapplies to Slaves and Repeaters. This parameter is not used by the Master.Because the Slave has the advantage of receiving acknowledgements fromthe Master, it is not necessary to blindly retransmit each packet. If the Slavedoes not get an acknowledgement on the next hop, it will retransmit itspacket. This will continue until the Packet Retry Limit is reached or anacknowledgement is received. If the limit is reached, the modem will giveup and discard the data. Valid settings are 0 to 255 retries. The defaultvalue is 2.The Repeater makes use of this parameter when it is tuned to its PrimaryHopping Pattern and is acting like a Slave.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 23S Register 115 - Packet Repeat IntervalA parameter that is specific to Slaves and Repeaters is the Packet RepeatInterval.The allowable settings are 1 through 255. The default is 1.This parameter defines a range of random numbers that the Slave will use asthe next slot in which it will attempt to send the packet. For example, if thisregister is set to 7, the Slave will choose a number between one and seven asthe next slot in which to transmit. Suppose the random number generatorpicks 5, then the Slave will transmit in the fifth time slot. A Slave willtransmit a maximum of once per hopping interval, however, depending onthe duration of the hopping interval and the maximum packet size, morethan one slot per hop is potentially available. The Slave will transmit morefrequently when a Repeat Interval with a smaller range is selected. Choose1 to have the Slave transmit in the first available slot. Choose higherintervals for less frequent transmission, or to avoid collisions between manySlaves in the system.S Register 117 - Modbus ModeModbus Mode allows for the MHX-2400 to be fully Modbus compatible.Please contact Microhard Systems for assistance when configuring the unitfor Modbus operation. Optimal Modbus settings rely on several other SRegister parameters.The allowable settings for this register are:*0 Disabled1Enabled
24 MHX-2400 Operating Manual: Chapter 3 Configuration OptionsS Register 120 - RTS/DCD FramingS Register 121 - DCD TimeoutThe MHX-2400 supports two special types of data framing:• Input (or RTS/CTS) Data Framing; and,• Output (or DCD) Data FramingInput Data Framing is enabled by configuring the Handshaking Parameter as&K2. This type of framing makes use of the S120 parameter as illustratedin Figure 5. Parameter S120 can be set to any value between 0 and 254 ms.RTSCTSTXDS120 (ms)Data going into MHX-9100 to 1 msFigure 5 - Input Data FramingTo enable output (DCD) data framing, set the Data Carrier Detect parameteras &C2. This type of framing uses both S120 and S121 registers as shownin Figure 6. Valid ranges for each parameter are 0 to 254 ms.DCDRXD Data leaving MHX-910S120 (ms) S121 (ms)Figure 6 - Output Data FramingS Register 123 - RSSI ReadingThis register displays the average signal strength in dBm over the previousfour hop intervals. Valid RSSI readings apply only to units configured asSlave or Repeater.
MHX-2400 Operating Manual: Chapter 3 Configuration Options 25
26 MHX-2400 Operating Manual: Appendix A. Modem Command SummaryA. Modem Command SummaryThe following provides a command summary for the MHX-2400 module. Factory settings are denoted with a ‘*’.AT CommandsAAnswerECommand EchoE0 No Echo* E1 Command EchoIIdentificationI0 Product CodeI2 ROM Checksum testI3 Firmware VersionI4 Firmware DateI5 CopyrightI6 Firmware TimeOOn-line ModeQQuiet Mode* Q0 Enables Result CodesQ1 Disables Result CodesVResult Codes DisplayV0 Display as Numbers* V1 Display as WordsWConnection Result* W0 Reports DTE as CONNECT xxxxW1 Reports computer (DTE) rate and wireless ratebetween modems as CARRIER xxxx.W2 Reports DCE as CONNECT xxxxZReset and load stored configuration&C DCD (Data Carrier Detect)&C0 DCD is always on* &C1 DCD is on when modems are synchronized&C2 DCD used for output data framing&D DTR (Data Terminal Ready)&D0 DTR ignored* &D2 DTR disconnects and switches to command&D3 DTR disconnects and resets modem&F Load Factory Default&F1 Master&F2 Slave&F3 Repeater&F4 Slave through Repeater&K Handshaking&K0 Disable Handshaking&K2 RTS/CTS Input Framing* &K3 Enable Handshaking&S DSR (Data Set Ready)&S0 DSR is always on* &S1 DSR on in data, off in command mode&V View Configuration&W Write configuration to memorySxx? Read S register valueSxx=yy Set S register valueResult Codes0OK 12 CONNECT 96003NO CARRIER 13 CONNECT 144004ERROR 14 CONNECT 192007CONNECT 2400 15 CONNECT 288008CONNECT 3600 17 CONNECT 384009CONNECT 4800 18 CONNECT 5760010 CONNECT 7200 33 CONNECT 11520064 CARRIER 20000 62 CARRIER 45000S RegistersS0 Auto Answer [0...255]0 = power up in Command Mode,non-zero = power up in Data ModeS2 Escape code [0...255] default ‘+’S3 CR character [0...255] default <cr>S4 Line Feed [0...255] default <lf>S5 Backspace [0...255] default <bs>S101 Operating Mode1 - Master Point to Multipoint2 - Master Point to Point3 - Slave4 - RepeaterS102 Serial Baud Rate*1 = 115200, 2 = 57600, 3 = 384004 = 28800, 5 = 19200, 6 = 144007 = 9600, 8 = 7200, 9 = 4800,10 = 3600, 11 = 2400S103 Wireless Link Rate2 = Fast w/o FEC*4 = Fast with FECS104 Network Address [0...65535]S105 Unit Address [1...65535]S106 Primary Hopping Pattern [0...50]S206 Secondary Hopping Pattern [0...50]S107 Encryption Key [0...65535]S108 Output Power Level0 = 10 mW, 1 = 50 mW, *2 = 100 mW, 3 = 250 mW4 = 500 mW, 5 = 750 mW, 6 = 1WS109 Hopping Interval1 = 8 msec, 2 = 12 msec, 3 = 16 msec,4 = 20 msec, 5 = 30 msec, 6 = 45 msec,7 = 80 msec, *8 = 120 msecS110 Data Format* 1 = 8N1, 2 = 8N2, 3 = 8E1, 4 = 8O15 = 7N1, 6 = 7N2, 7 = 7E1, 8 = 7O19 = 7E2, 10 = 7O2, 11 = 9N1S111 Packet Minimum Size [1...Maximum Size]S112 Packet Maximum Size [2...255]S113 Packet Retransmissions [0...255]S213 Packet Retry Limit [0...255]S115 Packet Repeat Interval [1..255]Default = 1S116 Packet Character Timeout [0...254 ms]S117 Modbus Mode*0 = Disabled, 1 = EnabledS120 RTS/DCD Framing Interval [0...254 ms]S121 DCD Timeout [0...254 ms]
MHX-2400 Operating Manual: RS-232 Interface and Cables 27
MHX-2400 Operating Manual: Appendix B Serial Interface 29B. Serial InterfaceModem(DCE)SignalHostMicroprocessor(DTE)1 DCD →IN2 RX →IN3← TX  OUT4← DTR  OUT5 SG →IN6 DSR →IN7← RTS  OUT8 CTS →INArrows denote the direction thatsignals are asserted (e.g., DCDoriginates at the DCE and tells theDTE that a carrier is present).The MHX-2400 module uses 8 pins on the header connector forasynchronous serial I/O. The interface conforms to standard RS-232 signalswithout level shifting, so direct connection to a host microprocessor ispossible.The signals in the asynchronous serial interface are described below:DCD Data Carrier Detect - Output from Modem - When asserted (TTL low),DCD informs the DTE that a communications link has been established withanother MHX-2400.RX Receive Data - Output from Modem - Signals transferred from the MHX-2400 are received by the DTE via RX.TX Transmit Data - Input to Modem - Signals are transmitted from the DTE viaTX to the MHX-2400.DTR Data Terminal Ready - Input to Modem - Asserted (TTL low) by the DTE toinform the modem that it is alive and ready for communications.SG Signal Ground - Provides a ground reference for all signals transmitted byboth DTE and DCE.DSR Data Set Ready - Output from Modem - Asserted (TTL low) by the DCE toinform the DTE that it is alive and ready for communications. DSR is themodem’s equivalent of the DTR signal.RTS Request to Send - Input to Modem - A “handshaking” signal which isasserted by the DTE (TTL low) when it is ready. When hardwarehandshaking is used, the RTS signal indicates to the DCE that the host canreceive data.CTS Clear to Send - Output from Modem - A “handshaking” signal which isasserted by the DCE (TTL low) when it has enabled communications andtransmission from the DTE can commence. When hardware handshaking isused, the CTS signal indicates to the host that the DCE can receive data.Notes: It is typical to refer to RX and TX from the perspective of the DTE. This should bekept in mind when looking at signals relative to the modem (DCE); the modemtransmits data on the RX line, and receives on TX.“DCE” and “modem” are often synonymous since a modem is typically a DCE device.“DTE” is, in most applications, a device such as a host microprocessor.
30 MHX-2400 Operating Manual: Appendix B Serial Interface
MHX-2400 Operating Manual: Appendix C Sample Schematic Diagram 31C. Sample Schematic DiagramThe following is a sample microprocessor implementation with a MICROCHIP PIC 16C74 and the MHX-2400. The MHX-2400 performs no level shifting on the serial port, so direct connection to the host microprocessor is possible.DO NOT CONNECT THE MHX-2400 TO RS 232 DRIVER OUTPUTS. DAMAGE TO THE UNIT MAY RESULT.On this implementation, the onboard SCI of the PIC 16C74 is directly connected pins 2 and 3 of the MHX-2400. The bi-directional Port D is used for asserting or monitoring control signals from the MHX-2400.The RESET and CONFIG signals are momentary active low signals asserted by the host microprocessor.RESET initializes the MHX-2400 and places the system in a known state. This signal should be set high after the hostmicroprocessor has been reset.The CONFIG line is reserved for factory use. This signal should be set high.RXDTXDDCDDTRDSRRTSCTSCONFIGRESETPIC16C74 MHX-90023146783231Power Connections not shownRC7RC6RD0RD1RD2RD3RD4RD5RD6
32 MHX-2400 Operating Manual: Appendix C Sample Schematic Diagram
MHX-2400 Operating Manual: Appendix D. Factory Default Settings 33D. Factory Default SettingsAT&F1 - Master Default SettingsE1, Q0, V1, W0, S0=0, S2=43, S3=13, S4=10, S5=8DCD &C1 (On)DTR &D0 (DTR is ignored)Framing &E0 (Disabled)Handshaking &K3 (Enabled)DSR &S1 (On in Data, Off in Command)Operating Mode S101=1 (Master P-MP)Serial Baud Rate S102=1 (115kbaud)Wireless Link Rate S103=4 (Fast, FEC)Network Address S104=1Unit Address S105=1Primary Hop Pattern S106=0Encryption Key S107=1Output Power S108=2 (100mW)Hop Interval S109=8Data Format S110=1 (8N1)Packet Minimum Size S111=1Packet Maximum Size S112=255Packet Retransmissions S113=2Packet Repeat Interval S115=1 (Don’t Care)Character Timeout (ms) S116=8Modbus Mode S117=0RTS/DCD Framing (ms) S120=0DCD Timeout (ms) S121=0Secondary Hop Pattern S206=2 (Don’t Care)Packet Retry Limit S213=2 (Don’t Care)AT&F2 - Slave Default SettingsE1, Q0, V1, W0, S0=1, S2=43, S3=13, S4=10, S5=8DCD &C1 (On when modems are synced)DTR &D0 (DTR is ignored)Framing &E0 (Disabled)Handshaking &K3 (Enabled)DSR &S1 (On in Data, Off in Command)Operating Mode S101=3 (Slave)Serial Baud Rate S102=1 (115kbaud)Wireless Link Rate S103=4 (Fast, FEC) (Set by Master)Network Address S104=1Unit Address S105=2Primary Hop Pattern S106=0Encryption Key S107=1Output Power S108=2 (100mW)Hop Interval S109=8 (Set by Master)Data Format S110=1 (8N1)Packet Minimum Size S111=1 (Set by Master)Packet Maximum Size S112=255 (Set by Master)Packet Retransmissions S113=2 (Don’t Care)Packet Repeat Interval S115=1Character Timeout (ms) S116=9Modbus Mode S117=0RTS/DCD Framing (ms) S120=0DCD Timeout (ms) S121=0Secondary Hop Pattern S206=2 (Don’t Care)Packet Retry Limit S213=2AT&F3 - Repeater Default SettingsE1, Q0, V1, W0, S0=1, S2=43, S3=13, S4=10, S5=8DCD &C1 (On when modems are synced)DTR &D0 (DTR is ignored)Framing &E0 (Disabled)Handshaking &K3 (Enabled)DSR &S1 (On in Data, Off in Command)Operating Mode S101=4 (Repeater)Serial Baud Rate S102=1 (115kbaud)Wireless Link Rate S103=4 (Fast, FEC) (Set by Master)Network Address S104=1Unit Address S105=3Primary Hop Pattern S106=0Encryption Key S107=1Output Power S108=2 (100mW)Hop Interval S109=8 (Set by Master)Data Format S110=1 (8N1)Packet Minimum Size S111=1 (Set by Master)Packet Maximum Size S112=255 (Set by Master)Packet Retransmissions S113=2Packet Repeat Interval S115=1Character Timeout (ms) S116=8Modbus Mode S117=0RTS/DCD Framing (ms) S120=0DCD Timeout (ms) S121=0Secondary Hop Pattern S206=2Packet Retry Limit S213=2AT&F4 -Slave Through Repeater Default SettingsE1, Q0, V1, W0, S0=1, S2=43, S3=13, S4=10, S5=8DCD &C1 (On when modems are synced)DTR &D0 (DTR is ignored)Framing &E0 (Disabled)Handshaking &K3 (Enabled)DSR &S1 (On in Data, Off in Command)Operating Mode S101=3 (Slave)Serial Baud Rate S102=1 (115kbaud)Wireless Link Rate S103=4 (Fast, FEC) (Set by Master)Network Address S104=1Unit Address S105=4Primary Hop Pattern S106=2Encryption Key S107=1Output Power S108=2 (100mW)Hop Interval S109=8 (Set by Master)Data Format S110=1 (8N1)Packet Minimum Size S111=1 (Set by Master)Packet Maximum Size S112=255 (Set by Master)Packet Retransmissions S113=2 (Don’t Care)Packet Repeat Interval S115=1Character Timeout (ms) S116=8Modbus Mode S117=0RTS/DCD Framing (ms) S120=0DCD Timeout (ms) S121=0Secondary Hop Pattern S206=2 (Don’t Care)Packet Retry Limit S213=2
34 MHX-2400 Operating Manual: Appendix D Factory Default Settings
MHX-2400 Operating Manual: Appendix E. Performance Tables 35E. Performance TablesThe scope of this appendix is to find the best possible performance and maximum packet size at different modes ofoperation. The setup assumes a baud rate of 115k, no retries and no retransmissions..HopIntervalOptimal Packet Size (bytes)Throughput(kbps)*1 (8 ms) 14 20Slave to Master 2 (12 ms) 66 52Communication. 3 (16 ms) 110 66(No Repeater) 4 (20 ms) 154 745 (30 ms) 255 83Link Rate = Fast 6 (45 ms) 255 56NO FEC 7 (80 ms) 255 318 (120 ms) 255 211 (8 ms) 5 4Slave to Master 2 (12 ms) 34 22Communication. 3 (16 ms) 54 28(No Repeater) 4 (20 ms) 76 325 (30 ms) 130 38Link Rate = Fast 6 (45 ms) 210 43WITH FEC 7 (80 ms) 255 308 (120 ms) 255 201 (8 ms) N/A N/ARepeater to 2 (12 ms) 3 1Master Direct 3 (16 ms) 22 13Communication. 4 (20 ms) 44 215 (30 ms) 101 32Link Rate = Fast 6 (45 ms) 178 39NO FEC 7 (80 ms) 255 318 (120 ms) 255 211 (8 ms) N/A N/ARepeater to 2 (12 ms) N/A N/AMaster Direct 3 (16 ms) 5 2Communication. 4 (20 ms) 16 65 (30 ms) 43 12Link Rate = Fast 6 (45 ms) 80 16WITH FEC 7 (80 ms) 174 208 (120 ms) 255 201 (8 ms) N/A N/ASlave to Master 2 (12 ms) 3 1Through One or 3 (16 ms) 22 13More Repeaters. 4 (20 ms) 43 215 (30 ms) 93 31Link Rate = Fast 6 (45 ms) 174 38NO FEC 7 (80 ms) 255 318 (120 ms) 255 211 (8 ms) N/A N/ASlave to Master 2 (12 ms) N/A N/AThrough One or 3 (16 ms) N/A N/AMore Repeaters. 4 (20 ms) 14 65 (30 ms) 40 12Link Rate = Fast 6 (45 ms) 80 16WITH FEC 7 (80 ms) 174 198 (120 ms) 255 20
36 MHX-2400 Operating Manual: Appendix E. Performance Tables
MHX-2400 Operating Manual: Appendix F. Hopping Patterns 37F. Hopping PatternsThis Appendix provides a guide for selecting appropriate hopping patterns (S106,S206). Thereare 49 hopping patterns: Patterns have been designed to notch out certain segments of the ISMband.Pattern Number Spectrum Used0 - 7 2.4012 - 2.4824 GHz8 - 10 2.4012 - 2.4312 GHz11 - 13 2.4052 - 2.4352 GHz14 - 16 2.4092 - 2.4392 GHz17 - 19 2.4132 - 2.4432 GHz20 - 22 2.4172 - 2.4472 GHz23 - 25 2.4212 - 2.4512 GHz26 - 28 2.4252 - 2.4552 GHz29 - 31 2.4292 - 2.4592 GHz32 - 34 2.4332 - 2.4632 GHz35 - 37 2.4372 - 2.4672 GHz38 - 40 2.4412 - 2.4712 GHz41 - 43 2.4452 - 2.4752 GHz44 - 46 2.4492 - 2.4792 GHz47 - 48 2.4520 - 2.4820 GHzPatterns 44 to 48 may be manually edited by entering AT&H at the Command Line. Each pattern must use a channelonly once, and must consist of exactly 76 channels. There are 202 channels available ranging from Channel 1 at2.4016 GHz up to Channel 202 at 2.4820 GHz
38 MHX-2400 Operating Manual: Appendix F. Hopping Patterns
MHX-2400 Operating Manual: Appendix G. Technical Specifications 39G. Technical SpecificationsElectrical/PhysicalData Interface Asynchronous Serial Port, TTL LevelsSignals Sig. Gnd, TX, RX, DCD, DSR, DTR, RTS, CTSBandwidth / Data Rate 2,400 - 115,200 bps, uncompressed half-duplex,Approx. 100 kbps sustained in intelligent asymmetrical full-duplextransmission modeCommunications Range130 kilometres (19 miles)Power Requirements 5 VDC, 1.0 AmpPower Consumption 700 mA max, 450 mA typical at 1W transmit; 200 mA receiveOperating Frequency 2.4000 GHz to 2.4835 GHzSystem Gain 135 dBSensitivity -105 dBmOutput Power 10, 50, 100, 250, 500, 750, 1000mW (user-selectable)Spreading Code Frequency HoppingHopping Patterns 20 pseudo-random, user-selectableError Detection CRC-16 with auto re-transmitError Correction User-selectable Forward Error Correction (FEC)Dimensions (LxWxH) Encl: 3.5” x 2.1” x 1.” (90 mm x 53 mm x 25 mm)Weight 75 gramsOperating Environment Temperature: -40 to +70°CHumidity: 5 to 95%, non-condensingStorage Temperature -40 to 90°C1. Clear line-of-sight, elevated high-gain antennas.
40 MHX-2400 Operating Manual: Appendix G. Technical Specifications
MHX-2400 Operating Manual: Appendix H. Glossary 41H. GlossaryTerminology Used in the MHX-2400 Operating ManualAsynchronous communications A method oftelecommunications in which units of single bytesof data are sent separately and at an arbitrary time(not periodically or referenced to a clock). Bytesare “padded” with start and stop bits to distinguisheach as a unit for the receiving end, which neednot be synchronized with the sending terminal.Attenuation The loss of signal power throughequipment, lines/cables, or other transmissiondevices. Measured in decibels (dB).Bandwidth The information-carrying capacity of adata transmission medium or device, usuallyexpressed in bits/second (bps).Baud Unit of signaling speed equivalent to thenumber of discrete conditions or events persecond. If each signal event represents only onebit condition, then baud rate equals bits persecond (bps) – this is generally true of the serialdata port, so baud and bps have been usedinterchangeably in this manual when referring tothe serial port; this is not always the case duringthe DCE-to-DCE communications, where anumber of modulation techniques are used toincrease the bps rate over the baud rate.Bit The smallest unit of information in a binarysystem, represented by either a 1 or 0.Abbreviated “b”.Bits per second (b/s or bps) A measure of datatransmission rate in serial communications. Alsosee baud.Byte A group of bits, generally 8 bits in length. Abyte typically represents a character of data.Abbreviated “B”.Characters per second (cps) A measure of datatransmission rate for common exchanges of data.A character is usually represented by 10 bits: an 8-bit byte plus two additional bits for marking thestart and stop. Thus, in most cases (but notalways), cps is related to bits per second (bps) bya 1:10 ratio.CRC (Cyclic Redundancy Check) An error-detectionscheme for transmitted data. Performed by usinga polynomial algorithm on data, and appending achecksum to the end of the packet. At thereceiving end, a similar algorithm is performedand checked against the transmitted checksum.Crossover cable (Also known as rollover, null-modem, or modem-eliminator cable) A cablewhich allows direct DTE-to-DTE connectionwithout intermediate DCEs typically used tobridge the two communicating devices. Can alsobe used to make cabled DCE-to-DCE connections.The name is derived from “crossing” or “rolling”several lines, including the TX and RX lines sothat transmitted data from one DTE is received onthe RX pin of the other DTE and vice-versa.Data Communications Equipment (DCE, alsoreferred to as Data Circuit-TerminatingEquipment, Data Set) A device which facilitates acommunications connection between DataTerminal Equipment (DTEs). Often, two or morecompatible DCE devices are used to “bridge”DTEs which need to exchange data. A DCEperforms signal encoding, decoding, andconversion of data sent/received by the DTE, andtransmits/receives data with another DCE.Common example is a modem.Data Terminal Equipment (DTE) An end-device which sends/receives data to/from a DCE,often providing a user-interface for informationexchange. Common examples are computers,terminals, and printers.dBm Stands for “Decibels referenced to onemilliwatt (1 mW)”. A standard unit of powerlevel commonly used in RF and communicationswork. n dBm is equal to 10(n/10) milliwatt, so0dBm = 1mW, -10dBm = 0.1mW, -20dBm =0.01mW, etc.DCE See Data Communications Equipment.DTE See Data Terminal Equipment.Flow Control A method of moderating thetransmission of data so that all devices within thecommunications link (DTEs and DCEs) transmitand receive only as much data as they can handleat once. This prevents devices from sending datawhich cannot be received at the other end due toconditions such as a full buffer or hardware not ina ready state. This is ideally handled by hardwareusing flow-control and handshaking signals, but
42 MHX-2400 Operating Manual: Appendix H . Glossarycan be controlled also by software using X-ON/X-OFF (transmitter on/off) commands.Frequency-hopping A type of spread spectrumcommunication whereby the carrier frequencyused between transmitter and receiver changesrepeatedly in a synchronized fashion according toa specified algorithm or table. This minimizesunauthorized jamming (interference) andinterception of telecommunications.Full-duplex Where data can be transmitted,simultaneously and independently, bi-directionally.Half duplex Exists when the communicationsmedium supports bi-directional transmission, butdata can only travel in one direction at the sametime.Handshaking A flow-control procedure forestablishing data communications wherebydevices indicate that data is to be sent and awaitappropriate signals that allow them to proceed.Line-of-sight Condition in which a transmittedsignal can reach its destination by travelling astraight path, without being absorbed and/orbounced by objects in its path.Master The station which controls and/or polls oneor more Slave stations in a point-to-point or point-to-multipoint network. Often functions as a serveror hub for the network.Non-volatile memory Memory which retainsinformation which is written to it.Null modem cable See Crossover cable.Point-to-point A simple communications networkin which only two DTEs are participants.Point-to-multipoint A communications networkin which a Master DTE communicates with two ormore Slave DTEs.Repeater A device which automatically amplifiesor restores signals to compensate for distortionand/or attenuation prior to retransmission. Arepeater is typically used to extend the distancefor which data can be reliably transmitted using aparticular medium or communications device.RS-232 (Recommended Standard 232; moreaccurately, RS-232C or EIA/TIA-232E) Definedby the EIA, a widely known standard electricaland physical interface for linking DCEs and DTEsfor serial data communications. Traditionallyspecifies a 25-pin D-sub connector, althoughmany newer devices use a compact 9-pinconnector with only the essential signaling linesused in asynchronous serial communications.Lines have two possible states: “high” (on, active,asserted, carrying +3 to +25 V) or “low” (off,inactive, disasserted, carrying -3 to -25 V).RTU (Remote Terminal Unit) A common termdescribing a DTE device which is part of a wide-area network. Often a RTU performs data I/O andtransmits the data to a centralized station.Serial communications A common mode ofdata transmission whereby character bits are sentsequentially, one at a time, using the samesignaling line. Contrast with parallelcommunications where all bits of a byte aretransmitted at once, usually requiring a signal linefor each bit.Shielded cable Interface medium which isinternally shrouded by a protective sheath tominimize external electromagnetic interference(“noise”).Slave A station which is controlled and/or polled bythe Master station for communications. Typicallyrepresents one end of a point-to-point connection,or one of the terminal nodes in a point-to-multipoint network. Often a RTU is linked by aSlave DCE.Spread spectrum A method of transmitting asignal over a wider bandwidth (using severalfrequencies) than the minimum necessary for theoriginally narrowband signal. A number oftechniques are used to achieve spread spectrumtelecommunications, including frequency hopping.Spread spectrum provides the possibility ofsharing the same band amongst many users whileincreasing the tolerance to interference and noise,and enhancing privacy of communications.Throughput A measure of the rate of data trans-mission passing through a data communicationsystem, often expressed as bits or characters persecond (bps or cps).

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