can I use two chasses and two 9401s for more counting channels?

[dav2010]

Hi,

I am currently using cDAQ9174 and NI 9401 and the four counters in the chassis to measure the periods of 4 separate (simultaneous) encoders in a vi.  All four encoders are running at the same time, and the vi measures them all in a single execution; not truly simultaneously, but, within the timing of a WHILE loop.  Actually, I suppose it measures the periods in a serial fashion.

I want to add more encoders to my hardware system, and measure their periods within the same vi.  So, can I add another chassis and another 9401, and measure periods of up to 8 encoders this way within the same vi on the same PC?  Will the vi recognize more counters than a single chassis has?

Will I face new errors with lots of encoders?

Thanks,

Dave

[Mockingbird]

Hi,

The easy answer is that yes you can do this. But you would have to configure your devices in MAX and you would have to also modify your VI to take in the inputs from the second device. How is your current vi interfacing with your cDAQ chasis? Are you using the DAQmx vis?

[dav2010]

Hi Gabriel,

I am using DAQmx to read the periods, yes.  Here is a sample of the code I was using for reading three periods.  I want to extend this from 3 to 5 period readings, but, the chassis has only 4 counters.  Do I just plug in the extra chassis to a different USB port on the PC and the VI will find both chasses?

Dave

[Mockingbird]

Hi,

Yes, you should be able to plug the extra chasis to a different USB port on the PC and when it's identified in MAX you can configure it's name and the counters will show up in the VI as selectable in the "Counter" control

[LabViewser27]

Follow up question. I am in a similar situation using the 9401 cards. I have four separate encoders that I need to read from. I see in the pinout for the 9401, that the counter pins overlap (see screenshot). For example, pin 20 is the A channel for counter 1 and is simultaneously the B channel for counter 3. Is it possible to still use all four counters on one card at the same time since I would need to wire channels on multiple encoders to the same pin?