HD Digital Output not turning On



I have a SNAP-PAC-R1 turning on relays using a SNAP-ODC-32-SRC. Intermittently I have one particular output that does not turn on (IVAL turns ON but XVAL stays OFF). No error is generated. I have worked around the problem by continuously turning on the point when it is needed. Is there a way to check the XVAL of a digital output point so I can record exactly when this error occurs and log the frequency? Not sure if the memory map read commands copies the IVAL or XVAL of output points, since these should always be the same.

p.s. I have contacted support and they recommended I re-seat all i/o and controller and make sure modules are screwed down; I did this but it didn’t help.


Hello Corey,

I strongly urge to you continue working with product support because it sounds like the problem could still be in a variety of places (the module/wiring, the controller, your logic). Before you can make it go away for good you’d need to narrow that down. You don’t have an extra SNAP-PAC-R1 you could swap with this one? And/or an extra SNAP-ODC-32-SRC? Does the problem happen frequently enough that you’d be sure if/when it’s gone?

Anyway, to answer your question, when you test this module with PAC Manager (via the mem map), you are accessing that XVAL (external) vs. IVAL (internal/software). Ditto when you read the mem map value via your strategy. I’d recommend you stop/clear the strategy if you can to make sure your strategy isn’t referencing that point somewhere you didn’t realize, then test it w/PAC Manager. But as I mentioned earlier, check with support in the case there’s something wrong with the -R1 or the module.