How do have your DAQ use multiple channels?

[person89898]

I apologize if the question has been asked before, but I'm having a hard figuring out how to word it. Basically, I want my counter.vi to take in data from three different channels which in my .vi, I've labled as counter, counter 1, and counter 2. To this end, I  put  0 in counter, 1 in counter 2, and 2 in counter 3(if this doesn't make sense, look at my vi.) The problem is that for some reason, all of the counters are taking data from channel 0, and not 1 or 2.

I also seem to have this problem with my .VI where the amplitude has these inexplicable jumps, and I don't know what to do about it. It'll say I have 4 billion pulses, then go down to 20 or so.

[person89898]

Oh, and here's my .vi.

[person89898]

Status update: Because I'm using a DAQ-STC, it only has 2 terminals(maybe that's what I meant by channels) that can be used for counting. However, I still have a problem because the DAQ is only reading from one terminal out of the 2 that are plugged up.

[Joseph-S]

Hi person89898,

It looks like you're using the Traditional DAQ drivers. Which DAQ card are you using?

[person89898]

I'm sorry for the late reply, but I don't know and I can't check, though I'll try. All I know is that I'm using the DAQ-STC.Is there a default card? It's probably that if there is one.

[Joseph-S]

Hi person89898,

Many of our DAQ cards use the Synchronization and Timing Chip (STC). I wanted to know the model number to see if our newer device drivers (DAQmx) are compatible, as they are generally easier to use than the legacy drivers. If you can find the DAQ model number, that would be great, otherwise I can still try to help you with this application.

[person89898]

Actually, I'm pretty sure we were using a DAQmx before. Not sure why we switched to STC. I remember something about it being compatible with what we have. I've sent an email asking what the number is though just in case.

[person89898]

Okay, just asked mentor. It's a DAQ PAD 6020E.

[Joseph-S]

Hi person89898,

Your DAQ-PAD device is only supported by the legacy drivers (NI-DAQ) and not the newer drivers (NI-DAQmx), as seen here: http://download.ni.com/support/softlib/multifunction_daq/traditionalnidaq/7.4/readme.html (search for "DAQPad-6020E").

Also, according to the latest legacy drivers manual (http://download.ni.com/support/softlib/multifunction_daq/traditionalnidaq/7.4.4/nidaq_readme_traditi...), there are a couple performance points that you should keep in mind for this particular device as it is quite old. This document also seems to describe the problem you are facing: http://digital.ni.com/public.nsf/allkb/1ECDAC3EC89B43F38625719500679683. I am investigating the fix that is referred to in this document which involves editing an INI file. I will let you know what I find. Also, as the legacy drivers are not compatible with Windows 7, I will have to test your code on a virtual machine running Windows XP. I'll also let you know what I find when this is up and running. In the meantime, please look through the documents I have listed here and see if they help to shed any light on your issue.

[person89898]

Okay, to solve the problem, I ended up using the a different .vi than the count events one. I now can read from both channels. However, it completely screws with my Shift registers. I hooked the DAQ up to a function generator, and it seems that the pulse count zigzags while steadily ascending. Somtimes it just zigzags from 4 mill to 0 and back again. 

Here's the new .vi and a screenshot of what I'm talking about.

http://imageshack.us/g/192/shiftregisterproblem.png/

http://imageshack.us/photo/my-images/560/idontevenp.png/