1756-OF6CI output card - broken wire signal or equivalent?

[bboytaktix]

Good afternoon forum members.


We recently had a fuse blow on the wiring between a 1756-OF6CI analog out card and a control valve (which we have no feedback for - only the 0-100% output). Took a little longer to troubleshoot since we have no feedback and we also don't monitor individual channel status of the card. For input cards (1756-IF8H or IF16H), it's easy enough to use the under-range/over-range or broken wire signal to troubleshoot a blown fuse or bad connection, and activate an alarm. I have been told by our local consultant-technician that there is an equivalent monitoring bit for output cards. Reading the instruction manual for the 1756-I/O cards, the fault channel bits do not seem to have this type of function for the 1756-OF6CI. The fault bits only seem to look at the requested output values, and at the connection between card and PLC itself as far as I can tell. Am I missing something?



thanks for your help

 

[Rippey574]

I think I understand what you are looking for, just a bit that says the wire has opened correct?

Go here
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1756-um009_-en-p.pdf

Then type 149 for the page.

Look at "Channel Status Words" near the bottom of that page, it can indicate which channel has an open wire.

This is for integer not float mode.

Forgot to add, pg. 170 indicates their is only 1 status word for all channels

 

[bboytaktix]

I think I understand what you are looking for, just a bit that says the wire has opened correct?

Go here
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1756-um009_-en-p.pdf

Then type 149 for the page.

Look at "Channel Status Words" near the bottom of that page, it can indicate which channel has an open wire.

This is for integer not float mode.

Forgot to add, pg. 170 indicates their is only 1 status word for all channels

Hi Michael,

thanks for the response. That would indeed be the status bit we are looking for, although the reference you supplied seems to be only for OF4 or OF8 cards. We most commonly use the OF6CI cards in float mode, and it seems those bits do not exist for these cards from what I can tell in the manual. We will have to run some tests to see if the 'channel fault' bit will activate when we break connection/remove wire.