Instructions For Setting Up Stepper Motor

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Instructions for setting up stepper motor:

1. Matlab setup

Matlab R2011a, Data Acquisition toolbox and Instrument

Control Toolbox. (Image acquisition toolbox is needed if

you want to use it with the extended experiment of ping

pong balls on stepper motor later).

Do not forget to right click on Matlab and select “run it as

an administrator”.

2. Assemble NI

USB 6008 with

the control

box (Do not

hookup to

computer yet)

NI USB 6000 has analog and digital channels. The stepper

motor has two photocells. These are connected to the

analog portion through the control box. The control box

has clock and direction that are connected to the digital

portion.

You will need connection wires to connect the control

box to ground and NI USB.

USB6008 digital port 17 (P0.0) should be connected to

direction control signal, port 18 (P0.1) should be

connected to clock signal. USB-6008 analog port 8 (AI2)

should be connected to 0 degree photocell and port 11

(AI3) should be connected to 90 degree photocell.

3. NI-Software

a. Install the NI- DAQmx 9.3 version from this website

compatible with your OS. The software takes a bit

long to install. Follow the directions as may pop-up

during the installation. You will need to restart the

computer to see the software installed. It should

install NI Visa and a device monitor.

b. After you hookup the USB 6008 into the computer,

the necessary driver should get installed and wait

for a message to the effect “driver installed

correctly” or “your hardware/usb is ready to use”

c. Check to see if your device monitor by NI or Ni Max

software is able to see this device in the devices list.

This means that NI can “listen” to your USB. You

can use Self-Test and other tests available from Ni

Max to make sure the USB has passed those tests.

d. Open a Matlab session and type

daqhwinfo(‘nidaq’) to see USB 6008 adapter is

successfully installed. You should see the NI-US 6008

e. and a port in the output of this command.

4. Software from

NU

Store the files from NU in a working folder (where you will

work). You may want to keep a safe copy of these

elsewhere too so you can go back to the original.

Setup_dio.m, cc.m, cw.m, onerot.m, readcell.m,

move_a_while.m

Two of these files might require changes to use the port of

your USB. Specifically, in the files, setup_dio.m and

readcell.m. There is a line in each of these two files that

has a “dev1” or “Dev1”. You/Students may need to

change this to the port at which your USB is available.

The port associated with your NI- USB can be found by

typing daqhwinfo(‘nidaq’) at the matlab command

prompt. The output of this command will give you the

port (such as “Dev3”) at which the USB 6008 is available.

Use this value in the readcell.m and setup_dio.m files.

Save the changes. Do not change anything else in these

files.

5. Check or

troubleshoot

Matlab to USB

6008

connection

Type the following commands at the command prompt:

daqhwinfo(‘nidaq’)

You should see NI-USB 6008 in the list. If this is not seen,

type

daqregister('nidaq') to make sure that Matlab is able to

load the adapter.(For this you will need to run Matlab as

administrator. Right click on Matlab icon and select “run

as an administrator”). You may not want to give this

option to students).

On typing daqregister(‘nidaq’) if you get the following

error:

daqregister('nidaq')

ans =

Unable to load adaptor:

C:\MATLABR2007b\toolbox\daq\daq\private\mwnidaq.dll.

Driver files or DLL for the specified adaptor could not be

found or are not installed.

Then you will need to type in this command again

daqregister(‘nidaq’) after selecting to run it as an

administrator. If the driver software has been loaded

correctly, and you run as administrator, then you will get

the following message:

mwnidaq.dll was registered successfully.

6. Setup

Create a dio object.

dio = setup_dio;

A dio object will be created and port information will be

output.

Check that photocells are working correctly:

readcell(1)

readcell(2)

The readcell output should not be negative. It will mean

some problems with the photocell connections. Check

the units carefully for lose wires, and control box for

connections.

Check that stepper motor can rotate:

onerot

The dial should turn either clockwise or counterclockwise.

To turn counterclockwise, type (in that order):

cc;

onerot;

To turn clockwise, type (in that order):

cw;

onerot;

7. Simple

program

If your setup works correctly and the commands in #6

work correctly, you are ready for writing simple programs.

Loops:

For loops:

For loops are used for repeatative tasks when you know

the number of times you want to do those tasks.

For 100 loops, type:

for i= 1:100

onerot

end;

You can change the number of loops the rotations will

work.

While loops:

While loops are used for tasks to do until certain condition

is met. You do not necessarily know how many times you

will need to do the tasks until the condition is met.

While readcell(1)<1.0

Onerot

End;

Use Ctrl+C to terminate the program for any reason.

Determine Step size:

Type in a large number of steps (such as 1000) and note

down the total angle covered during those steps. You

may have to find how many times (n) the flag on the dial

crosses 0 or some particular angle and add any

additional angle it may have gone.

Total angle/number of steps = step size

Experiment with different number of steps to see how

many steps are needed to cover a 90 degree angle, a

180 degree angle and a 270 degree angle etc. You will

need to use this with your ping-pong ball experiment.

90/3.74 = approx.. 25 steps

180/3.74 approx. 48 steps.

270/3.74 approx. 73 steps