Electronic Systems Technology ESTEEM195EG-1 ESTEEM 195Eg User Manual Chapter 0 Front Cover 195Eg
Electronic Systems Technology ESTEEM 195Eg Chapter 0 Front Cover 195Eg
Contents
user manual ch 6 to 7
CHAPTER 6
SERIAL APPLICATIONS
Revised: 23 Jan 08 6-1 EST P/N AA107G
The ESTeem 195Eg is now available with an optional factory installed serial port that can provide RS-232 communication between
two or more serial devices using the wireless broadband link. The serial data is encapsulated and transferred as a standard Ethernet
packet over an operating 195Eg wireless Ethernet system. The configuration for a serial 195Eg network will be the same as an
Ethernet or a serial (RS-232) based communication network.
The serial interface option can be used to link two or more serial devices in a new or existing system. The serial data has very little
impact on the network bandwidth and will allow for both Ethernet and serial applications simultaneously. A few possible
applications would be installation of the 195Eg in an existing serial based network that was looking for future upgrade to an
Ethernet based system. Another would be using the high-bandwidth Ethernet connections to provide a link to remote video
hardware but also provide a serial link to the existing PLC in a SCADA type application.
SERIAL CONNECTIONS
The RJ-45 serial data port is the far-left port on face of the
195Eg (Figure 1). Using the ESTeem AA0621 interface
cable, the 195Eg can be connected to a standard DTE-device
(PC) with a male 9-pin Sub-D connector. The complete
cable configuration is available in Appendix C – Interface
Ports.
Second Ethernet Port
Installation of the serial option also includes installing a
second 10/100 Base-T Ethernet interface. This second
Ethernet port can be used to Bridge to the first Ethernet port
(ETH_0) and the wireless link to work as a two-port HUB
when configured in the AP Bridge mode. This second Ethernet port can also be configured as Router port between the wireless and
the first Ethernet port in AP Router mode (Figure 2).
AP Bridge Mode
In the AP Bridge mode, both Ethernet ports (ETH_0 and ETH_1) and the wireless port (WLAN_0) are configured for a common
subnet and share a common IP address.
AP Router Mode
In the AP Router mode, the two Ethernet ports (ETH_0 and ETH_1) will be on separate subnets. The primary Ethernet port
(ETH_0) is configured for Subnet A. The secondary Ethernet port (ETH_1) is bridged to the Wireless port (WLAN_0), sharing an
IP address and configured for Subnet B.
If desired, the secondary Ethernet Port (ETH_1) can be configured for a 3rd subnet (i.e. subnet C). This requires advanced
configuration and routing tables specific to the particular networks.
12 VDC Input
(Auxiliary
Connector )
Reset Switch RS-232
Configuration RJ-45 10/100BaseT
Ethernet Port
Transmit
LED
Receive
LED
Status
LED
Power over
Ethernet LED
Aux Power
LED
RS-232
Data Port
Second
Ethernet
Port
Figure 1: 195Eg Front Panel Overview
Bridge
Ethernet 1 Ethernet 2 Wireless
Router
Ethernet 1
Ethernet 2
Wireless
Subnet 1 Subnet 2
Figure 2: Bridge and Router Configuration for Ethernet Ports
CHAPTER 6
SERIAL APPLICATIONS
Revised: 23 Jan 08 6-2 EST P/N AA107G
SERIAL CONFIGURATION
Configuration of the serial port is completed during the standard setup of the 195Eg. After completion of the Repeater Peer
configuration screen, the Serial Port Setup screen (Figure 3) will be displayed. Each section in the Serial Port Setup screen is
described in detail with the following:
Enable the RS-232 Data Port
Enabling the serial data port allows the modem to send RS-232 data over the broadband wireless connection established with the
ESTeem repeater peers. The modem can be configured in a point-to-point or point-to-multipoint system. Select Yes if you wish to
enable the serial data port.
Figure 3: Serial Configuration Screen
CHAPTER 6
SERIAL APPLICATIONS
Revised: 23 Jan 08 6-3 EST P/N AA107G
Mode of Operation
There are two distinct modes of operation for the serial port in the 195Eg. The Redirector mode will provide two-way serial
communication between two or more serial devices, while the Terminal Server mode will allow serial communication to a specific
remote site by connecting through telnet or SSH. Select one of the following modes of operation:
Full Redirector Mode - This mode allows bi-directional RS-232 data communication with another ESTeem. The RS-232 data
transmission will appear transparent to the connected devices as if a serial cable is connected between the two ports. This mode
will also be used in a multi-point serial network were all serial devices will need bi-directional communication (Figure 4).
CHAPTER 6
SERIAL APPLICATIONS
Revised: 23 Jan 08 6-4 EST P/N AA107G
Terminal Server Mode - This mode of operation
translates RS-232 serial data into a network-oriented
terminal protocol, such as telnet or SSH. This mode
would be selected if an interactive RS-232 session at
remote locations is desired over the wireless Ethernet link
(Figure 5).
Baud Rate
Select the data rate of the RS-232 connection to match
your serial device.
Data Bits
Select the number of data bits on the RS-232 connection
to match your serial device.
Stop Bits
Select the number of stop bits on the RS-232 connection
to match your serial device.
Parity
Select the parity of the RS-232 connection to match your serial device.
Remote Site & Repeater
Repeater
Remote Site
Access Point
Bridge with
Repeater Mode
Remote Site
Access Point
Bridge with
Repeater
Mode
Access Point
Bridge with
Repeater
Mode
Access Point
Bridge with
Repeater Mode
Access Point
Bridge with
Repeater
Mode
Line-of-Sight Path
NOTE:
Repeater may be stand-
alone or attached to a
network or device.
Line-of-Sight Path
Line-of-Sight Path
Line-of-Sight Path
Line-of-Sight Path
Access Point
Bridge with
Repeater
Mode
Note:
Antenna’s shown are for
illustration purposes. There
are many antenna options
available depending on your
application.
Master PLC
RS-232 Data
Remote PLC
RS-232 Data
RS-232 Data
RS-232 Data
RS-232 Data
Figure 4: Serial Full Redirector Example
Access Point Bridge
with Repeater Mode
Line-of-Sight Path
54 Mbps
Access Point Bridge
with Repeater Mode
Remote SCADA Node
Access Point
Bridge with
Repeater Mode
Remote PLC
RS-232 Data
Telnet Session to
Remote 195Eg
Figure 5: Terminal Server Example
CHAPTER 6
SERIAL APPLICATIONS
Revised: 23 Jan 08 6-5 EST P/N AA107G
Flow Control
Select the type of data flow control used on the RS-232 connection. The ESTeem can support Hardware flow control (RTS/CTS
control lines) or Software Flow Control (XON/XOFF). Select None if no serial flow control is necessary.
Maximum Bridge Links for Multicast Packets
This value sets the maximum number of Ethernet bridge links that the multicast packets will be sent through when used in a multi-
point system. A multi-point serial network uses multicast packets (UDP) to send the data to more than one remote ESTeem. You
want to limit the number of network bridge links that these UDP packets will be passed through to make the network more efficient.
If you are using multiple ESTeem repeater links to send the serial data to remote locations, the value for the maximum bridge link
needs to be increased to a number greater than the longest repeater chain. For example, if you are using four repeater (peer) links to
send the serial data between two or more sites the number will need to be five (5) or greater (Figure 4).
Destination IP Address
The ESTeem configured for the correct destination IP and port number will send and receive the serial data from another modem.
Set the destination IP address for the ESTeem where the serial data will be sent. If sending to more than one ESTeem (Multipoint)
set to a multicast address (i.e 224.0.0.1).
Note: If you are using the ESTeem 195Eg in a multipoint application (multicast), you must have default Gateway configured in
the ESTeem set to the IP address of the Root Bridge modem.
Serial IP Port Number
The ESTeem configured for the correct destination IP and port number will send and receive the serial data from another modem.
Set the IP port numbers to match where the serial data will be sent. The serial data will not be sent if both the IP address and port
number are not correct.
Maximum Packet Size
This number represents the maximum size of the serial data packet in bytes. If the number of bytes of data in the serial port buffer
exceeds the maximum packet size before the timer or delimiter character is reached, the ESTeem will send forward the serial
packet. For example, if the maximum packet size is set to a value of 100, when the serial port receives 100 bytes the data will be
sent through the wireless connection.
Number of Milliseconds for Packetization
This number represents the time the ESTeem will hold data in the serial data buffer before sending to the remote ESTeem. This
feature is generally used if the serial data does not have a consistent packet length or delimiter character. For example, if the
number of milliseconds is set to a value of 10 the ESTeem will monitor the incoming serial data stream and any break in characters
longer than 10 milliseconds will cause the data will be sent through the wireless connection.
Delimiter Characters
Enabling and specifying a delimiter character will transmit the data in the serial buffer when the delimiter character is recognized in
the serial data stream. There are two unique delimiter characters that can be configured and enabled independently.
Terminal Server Control Lines
Enabling this feature will allow the ESTeem in the Terminal Server mode to read and generate modem control lines to the
connected device.
CHAPTER 7
REPEATING FEATURES
Revised: 23 Jan 08 7-1 EST P/N AA107G
To increase the wireless network’s area of coverage for
both indoor and outdoor applications, the ESTeem 195Eg
utilizes a custom repeating feature that allows increased
coverage areas without the added expense of hard cabling
or adding an additional point to point radio link.
With a conventional IEEE 802.11g or 802.11b Access
Point (AP) network, all of the APs have to be interfaced to
a common network either by hardwire, see Figure 1, or a
separate, dedicated RF backbone. The Model 195Eg can
create this RF backbone, bridge Ethernet networks connected to the wired Ethernet port and provide the wireless canopy for 802.11
clients simultaneously.
When programmed in any of the three Access Point (AP) Repeater Modes, the Model 195Eg will create a wireless network with
other Model 195Eg units in radio range that are programmed in the AP Repeater Peer table during setup. This feature adds the
increased functionality of repeaters to the typical Ethernet Bridge configuration.
ESTEEM MESH NETWORK
One of the most powerful features of the AP Repeater
Mode is the ability to input multiple communication
routes and designate the priority for each of these routes
to create a wireless Mesh network. The ESTeem Model
195Eg will automatically change communication routes in
the network if a route has failed. The new route will be
based upon the priority level set during configuration.
This wireless Meshing technology allows the RF network
to “self-heal” if any of the communication paths fail.
The routing priority is manually set during the
configuration of the 195Eg. A manual path configuration
is far superior to standard “self-discovery” networks,
because you have direct control over the best RF paths
and can easily identify any failed routes for easy
troubleshooting. For example, Figure 2 shows a typical
wireless Ethernet system used in the Water/Waste Water
Industry. The problem with a standard “self-discovery”
Mesh network is the selection of routes. Notice that the
communication between the Water Plant (Site A) and
Pump Site D has a marginal link, but it is the most direct
route between the Ethernet devices.
This scenario poses the question, which path will the network select? The ESTeem Mesh Network takes out the guessing games by
allowing the user to select and prioritize all communication routes in the system. In our example we would want the primary link to
go through Tank B (Repeater) and use the direct link only if this primary link fails. The following sections will show how this
completed.
Configuration
The configuration of the repeater paths is completed during setup of the Access Point modes. All three Access Point modes support
repeating and Meshing features. Figure 3 shows an example repeater peer table from the setup menus. For an ESTeem 195Eg to
communicate with another ESTeem 195Eg, Yes must be selected at the “Enable Repeater Capability.” Next, the Wireless LAN
(WLAN) MAC address of each Model 195Eg that will have direct communications must be added to the Repeater Peer List.
Figure 1: Conventional Access Point Diagram
Figure 2: Small Mesh Network Diagram
CHAPTER 7
REPEATING FEATURES
Revised: 23 Jan 08 7-2 EST P/N AA107G
Finally, enabling the link allows the corresponding 195Eg to be included in the communication routing. Mobile clients do not
require input in the repeater peer table. If multiple Mesh routes are configured, you will also need to set the values for Priority and
Path Costs (explained in Spanning Tree below). For multiple examples of repeater configurations, please refer to Chapter 5 of this
user’s manual.
SPANNING TREE PROTOCOL (STP)
The ESTeem Model 195Eg uses standard Ethernet Spanning Tree Protocol (STP) to determine the radio routing structure of the
wireless network. The primary purpose of STP is to make sure that “network loops” are not created. A network loop is having two
communication paths to the same destination where the remote device would receive the same data multiple times. If there were no
way to control the data flow, this data would be constantly passed around this loop causing a “packet storm” that would shut down
the entire network. The Spanning Tree Protocol will block all these redundant links.
The STP operation begins by determining which Ethernet device on the network will be the Root Bridge. All Ethernet networks
have a Root Bridge that is selected by the lowest MAC address. All path costs are evaluated against this Root Bridge device to
determine routing and which paths will be blocked. On a wired Ethernet network, the location of the Root Bridge is not really
important, but in a wireless network selection of the Root Bridge is critical to the wireless network routing. Let’s use one of the
Example network diagrams from Chapter 5 to continue the discussion (Figure 4).
Figure 3: Repeater Configuration Example
CHAPTER 7
REPEATING FEATURES
Revised: 23 Jan 08 7-3 EST P/N AA107G
The following sections describe the process of the STP in the ESTeem Model 195Eg as how it would happen in the above example.
Learning Phase - Once properly configured, each Model 195Eg will begin to search out the other Model 195Eg units in radio range
that are programmed in the AP Repeater Peer table. All Model 195Eg’s will calculate their routes to every Model 195Eg in the
network based upon the lowest “path cost” to the Root Bridge. Path cost is the total cost of transmitting a packet through the
wireless network to the Root Bridge. Note: The Root Bridge in a network should be the Model 195Eg where the majority of the
data flow is processed. In every wireless network of two or more radios, the Root Bridge should be user defined. If not defined, the
ESTeem 195Eg with the lowest MAC address will be designated as the Root Bridge.
In Figure 4, the Plant network (Example 1) is the most logical location for the Root Bridge based upon the amount of data flow.
Setting this site as the root bridge is discussed below in Root Bridge.
Blocking and Forwarding Phase – To ensure you do not have a network loop situation due to redundant paths in your wireless
network, the Model 195Eg will recognize and disable (block) one or more redundant links and provide back up links should the
primary link fail. This establishes a wireless mesh network with a series of forwarding links, based upon the shortest path cost to the
Root Bridge.
For example, looking at Figure 4, the Remote Building has two routes to the Root Bridge (Plant Network – Example #1); directly to
the site and through the repeater. The direct link between the two sites is the shortest route (lowest Path Cost) and will be selected
as the primary route unless overridden by manually changing the Path Cost in the configuration.
Access Point Router
with Repeater
Feature Enabled
10/100BaseT
HUB or Switch
Mobile
PLC
EtherStation
Mode
10/100BaseT
Access Point Bridge
with Repeater
Feature Enabled
Primary Repeater Path
Backup Repeater Path
Access Point Bridge
with Repeater
Feature Enabled
Mobile Vehicle
Single Ethernet Device
Example #4
S/N: 14004
Primary Repeater Path
Plant Network
Large Wired LAN
Example #1
S/N: E-14001
WLAN MAC=00:04:3F:00:09:01
Remote Building
Small Ethernet Wired LAN
Example #3
S/N: E-14003
WLAN MAC=00:04:3F:00:09:10
Stand-Alone Repeater Site
Example #2
S/N: E-14002
WLAN MAC= 00:04:3F:00:09:05
Network
Router
(Required)
Figure 4: Programming Example #1 Diagram
CHAPTER 7
REPEATING FEATURES
Revised: 23 Jan 08 7-4 EST P/N AA107G
Path Cost
If more than one communication path to the Root Bridge is found, the 195Eg must determine which route to take based upon the
lowest Path Cost. The default path cost to all links in the 195Eg network is 100. If the Path Costs are equal then the lowest MAC
address will determine the priority route. In the ESTeem Mesh Network we want to directly control all data flow so do not want
the routes to be automatically determined.
Looking again at our Example in Figure 4, if we made no changes to the default path cost of 100 (note values in Figure 3) the
lowest path cost would be direct from the Remote Building to the Root Bridge (Plant Network).
Link Description Number of Routes Total Path Cost
Direct from Remote Building 1 100
Remote Build to Root Bridge Through Repeater 2 200
To configure the 195Eg to select the repeater as the primary radio path, set the path cost value for the direct link greater than 200 to
make this the primary radio path. The lowest path cost will identify the highest priority. The Model 195Eg will use this routing,
but also switch to direct communication if the repeater were to disappear.
Root Bridge
In any Access Point Repeater network consisting of more than two sites, one Model 195Eg should be designated as the Root
Bridge. Only one Model 195Eg can be designated as the Root Bridge in a given network and should be located where the majority
of the Ethernet data flow is processed. This site may be the Master location in a SCADA network or could be configured at a
repeater site. Selection is important because all Model 195Eg’s NOT configured as the Root Bridge will choose routing based
upon the Path Cost to the Root Bridge. If you have any question as to which site in your AP Repeater application should be the
Root Bridge, contact ESTeem Customer Support at 509-735-9092 or e-mail your application to support@esteem.com.
The Root Bridge will be selected in one of two ways: the Root Bridge can be manually set (recommended) during the configuration
of the Repeater Peer table (Figure 3) or the Root Bridge designation will default to the lowest MAC address of all the Model
195Eg’s in the network. The manual Root Bridge configuration is located in the “Advanced Settings” section.
Figure 3: Repeater Configuration Example
CHAPTER 7
REPEATING FEATURES
Revised: 23 Jan 08 7-5 EST P/N AA107G
Redundant Backup
The ESTeem Model 195Eg configured in Access Point Repeater
mode will automatically function as a redundant backup if two
Model 195Eg’s are installed at the same location (Figure 7). If
two Model 195Eg’s are connected to the same HUB or Switch,
one of the Model 195Eg’s will be Blocked when the Spanning
Tree Protocol is completed. The network will continue to use
this route until any problem with the original Model 195Eg is
detected and the second Model 195Eg will begin operation at
that site.
Redundant Master Configuration – The configuration in
Figure 7 will also provide a redundant backup for the Master
Site (Root Bridge). Configure both Model 195Eg’s as Root
Bridges (see above) giving the primary Root Bridge a value of 1
and the secondary Root Bridge a value of 2.
Figure 7: Redundant Backup Diagram