-QNAN on Inputs

Other Opto Products
1

I am using a SNAP-OAC-EB2 with 12 analog input modules in a 16 slot rack. Each of the input modules has 8 analog inputs. I am measuring temperature with this system.

Every once in a while (about 1-2 times per week), all of the inputs into one module will produce a “-QNAN” for about 2 to 3 minutes, then resume working correctly. This has occurred on several different modules. Whenever it happens, it affects all 8 inputs into the module.

Anyone have any clues as to what might be causing this?

The SNAP system is connected to a Controllogix PLC with an ethernet connection through a Stratix 8000 switch with an expansion module (18 ports in total). The PLC and the switch are working normally.

2

Hello Kurt9,

Welcome to the forums!

Often that’s due to too-low voltage on the rack. Check out this video (click here) [/B][/U] for how to check that. In the video, Ben also mentions [U][B][URL=“http://www.opto22.com/site/documents/doc_drilldown.aspx?aid=1789”]this doc.

Do the occurrences of this problem correlate to other machinery coming on? Does it tend to happen more on modules furthest from the PAC on the rack?

Also don’t forget that Product Support is FREE! if you’re still having trouble.

-OptoMary