NI 9411 and Linear Encoder - Inverted travel

[DakotaFields]

Hi,

I've stumbled across an issue with two NI-9411s being used in a NI-9149 c-RIO to measure linear motion.  Each 9411 is used one at a time and they are reporting encoder output differently.  Here's the scenario:

1 - cRio chassis is being used

1 - quadrature encoder

1 - LabVIEW program

1 - DUT.

When I have 9411 - "A" plugged into the c-RIO and connected to encoder, the test item travel is reported as increasing.  

When I remove 9411 - "A" and plug 9411-"B" into the c-RIO, connect the exact same encoder to it, and move the DUT through the same travel motion, the travel is reported as decreasing.

The c-RIO and 9411's are brand new.

Is there a setting on the card that could have been changed somewhere, a bad card, or something else possibly?

Any insight would be helpful.

Thanks!

[RIObotics]

Hi Dakota,

Sounds like an interesting problem.  Are you placing 9411-A and 9411-B in exactly the same slot of the 9149 chassis?  If so, given that everything else about the system is the same (ex: same LabVIEW code, same PC, etc.), then the results from the 2 modules should be the same.  Also be sure to check the wiring for both of your modules is exactly the same, as the A and B phases may be swapped for the 2nd module, causing the reverse in direction.

BR

John

Add motion to LabVIEW in 30min or less - TENET EMotion
Finding it hard to source NI hardware? Try NI Trading Post

[DakotaFields]

John,

Yes, everything about the test system is exactly the same with the exception of the NI 9411 module.  I was utilizing one test system and just swapping the 9411s out.  Ended up sending the module back to NI for evaluation.

Thanks!