Unexpected Digital Input Results Troubleshooting

Updated Sep 25, 2019

Reported In

Hardware

  • NI-9375
  • sbRIO-9375
  • NI-9411
  • NI-9421
  • NI-9422
  • NI-9423
  • NI-9425
  • sbRIO-9425
  • NI-9426
  • NI-9435
  • NI-9437

Issue Details

My digital input task reads incorrect values. What causes that and how can I solve it?

Solution

Narrow down the cause of the problem.
  • Run a shipping example to confirm if it still gives unexpected results. If the example gives correct results, the issue might be on your code. NI encourages you to take advantage of the shipping examples. All the examples are developed and tested and documented¬†to show the correct way of using the software.
  • Utilize a digital output, a battery or any known source to generate the values of voltage needed for the Highs and Lows. Connect them to the digital inputs and see if this gives consistent expected results. If that is the case, then the source could be giving issues.
  • You may use a different line, port or modules, to dismiss hardware issues. For example, say you have modules A and B both are the same model. If using module A gives you wrong results, but using module B in the same chassis gives correct results, the cause could be a fault in module A.¬†
If you could not narrow down the cause of the problem, call NI support.

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