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XA2 VREF Failure Effects

Mike 2 years ago in Expansion modules / XA2, XS2 updated by Gustav Widén (System support) 1 year ago 1

This is a two part question regarding the criticality of VREFs for IQAN Modules.  We use an MD4 and XA2 in our system.  On the XA2, we use VREF to support a three axis joystick and one pressure transducer (4 VINs).


We received a report from the field that a short circuit between VREF and ground caused the XA2 module to fail completely resulting in "I/O No Contact" IQAN Error Message on the MD4.


Is this a typical or expected failure mode for an XA2 with a damaged 5V reference voltage regulator?  Or is it more likely there was a mis-diagnosis from the field?  I can't think of a way to validate this without destroying an otherwise healthy XA2.

Would this also be the case in an MC42?

If the VREF on the XA2 is just shorted to ground, it will keep operating and just report a VREF error. When the short is removed, it will recover. 

The same goes for MC4 and XC4, the VREFs on all modules are designed to handle short to ground.