NI-9237 External Excitation Issues

[tarmanan]

Describe the bug Unable to use External Excitation with the NI-9237 module and the EtherCAT custom device

To Reproduce Steps to reproduce the behavior:

1. Go to Slot Settings and set Excitation Voltage == External
2. Verify +10VDC at NI-9237 EXC+ and EXC-
3. Deploy Project
4. View channel[s]
5. Observe incorrect channel reading
   • Cause = incorrect math based on Excitation Voltage?

Expected behavior Channel reading output correct

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [Linux_64]
• Version [20.3 and 20.4]
• NI-9045

Additional context 1] This was an issue in a previous release - https://forums.ni.com/t5/NI-VeriStand/NI-9237-External-Excitation-VeriStand-2013-SP1/m-p/3088022?profile.language=en 2] Proper operation when Excitation Voltage == 10.0 Volts

[rtzoeller]

@tarmanan I can't easily confirm what the underlying issue was that was fixed in the 4.1.10 release, as it predates this Git repository. That said, I looked at the source for the NI 9237 in this custom device and it appears straightforward and correct.

There is no math in the custom device regarding the excitation voltage; the values are predefined:

All configuration options supported by the module in Scan Mode are exposed by the custom device, and the values are passed through directly to the driver. I was initially wary of the coercion dots on the property node, but they appear to be value-preserving casts.

My recommendation would be to contact NI support at support@ni.com or 1(800)531-5066 to investigate the behavior, as I don't believe the problem is within this VeriStand add-on.

[tarmanan]

Thank you very much for looking into this, @rtzoeller . I'll reach out to NI support.

[tarmanan]

I found that the issue was related to a specific gage [shaft gaged for torque] I was using and not related to the external excitation. Thank you again for looking into this.