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XA2 VREF Failure Effects

Mike 3 years ago in Expansion modules / XA2, XS2 • updated by Gustav Widén (System support) 3 years 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?

Gustav Widén (System support) 3 years ago

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. 

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