PCIe-6320 doesn't see encoder

[dstanisl]

I am trying to set up the PCIe-6320 with two rotary encoders to measure position.

I wired up my encoder (dual quadrature with A, B, Z, V+ and Gnd wires) to my PCIe-6320 DAQ through an SCB-68 connector block. I used an external power source for the encoder so all I connected was the A, B, and Z channels. I checked my wiring. Counter 0 uses pins 37, 45, and 3.

When I connect it, there are a few issues: In Measurement and Automation Explorer (MAX), I go to the Counter testing function and it does not register. Using a multimeter, when the encoder is not connected I get some kind of output from the three channels. But once I connect it to the DAQ, I get nothing.

The self-test works in the MAX software and the calibration seems to go successfully.

What could be the problem here? Is it possible that the DAQ is broken even though it passes the self-test?

[Brandon_B]

Hello dstanisl,

What version of DAQmx do you have on your computer?  Also, what type of encoder are you using and what is the value of V+ supposed to be?  There is an example on our community website which measures angular position of a quadrature encoder and allows you to select the decoding type and Z index.  I would suggest trying this example on all the counters on your device.  There is also a developer zone article on our website which shows you how to take quadrature encoder measurements.  Take a look at this as well and let me know if you have any questions.

Regards,

[dstanisl]

DAQmx: I'm not even sure what DAQmx is. Is it the set of DLLs that allows me to communicate with my DAQ? Is it Measurement and Automation Explorer (mine is v. 4.6.1f0, by the way)?

Encoder: I'm using an Accucoder 755A. It's a dual quadrature with index and open collector output. It takes 5-28V and I'm giving it 6V.

I tried running one of the example C# programs that installed with MAX but it did not detect encoder movement.

[AnalogKid2DigitalMan · Accepted solution]

I think I may know what is going on. The outputs are open collector, so you may need pull up resistors. See page 9 (page 7 in print) in the pdf file:

http://www.ctiautomation.net/PDF/Accu-Coder/Accu-Coder-Installation-Wiring-Guide.pdf

Since you are using an external supply, instead of tying the end of the resitor to your +VDC  (6 volts in your case) you should connect it to the +5 out that is probably available on your DAQ card. This will ensure that the outputs do not exceed TTL levels (5V). You will then need to tie the common or ground of your 6V supply to the digital GND of your DAQ card.

DAQmx are the drivers and vi's for the hardware. If you have MAX, you can check for presence and version of DAQ under the software listing in MAX.

Hope this helps.

-AK2DM

[dstanisl]

Thanks! That was it.

[AnalogKid2DigitalMan]

Cool! Glad I could 'emitter' a solution to the 'base' problem 🙂

Those gosh darn open collectors will get you (nearly) every time.

-AK2DM