Compact Logix I/O problem

Hello,

I am using an AB CompactLogix 1769-L35E processor with a 1769-OA16 output module. I have an MCR wired to my e-stop circuit that removes 120v from the VAC1 and VAC2 terminals on the OA16 module to kill all my outputs when an e-stop is activated. I've done this with SLC's in the past with no problems. I think it is a fairly common practice to do this. The problem I'm having with the Compact Logix is that when I restore the 120v to the OA16 module (ie reset my e-stop), my I/O stops responding for about 10 seconds. Basically, the I/O on the entire rack and two remote racks is re-initializing. AB tech support says that this should not happen. NO KIDDING! Has anyone here experienced this problem?

Thanks,
Chris

Have not experienced this problem Chris.
I have used several of this type of system in many machines. Yes, we do the same thing with E-STOP CCT's. We run through a safety relay though....
The card is monitored through the RACK.(EXPANDABLE THROUGH ADD-ON Cards)
This way, your card is ALWAYS powered on the bus. The fact that you are disconnecting L1 to the LINE side of the RELAY does not affect your I/O updated scan. This seems like you are having another problem that "seems" like your situation.
In other words, have you looked at the logic involved?
Recovery, 10 second delays....etc?

Thanks for the reply. I am not removing L1 power from the processor or power from the OA16 since it is powered from the Compact Bus of the PLC. I am simply removing the VAC1 and VAC2 power from the OA16, which is the supply for the 2 groups of outputs. I too am using a safety relay and my I/O power that feeds the OA16 is routed thru the safety contacts. My gut feeling is that upon restoring the VAC1 and VAC2 that there is some sort of inrush to the OA16 that causes an interruption in the Compact Bus. My next course of action is to replace the OA16. I think I may have a bad module.

That is the quickest and easiest solution for testing.
When I referenced L1, I meant your VAC1 and VAC2.
I have used this process exclusively, with no issues as you are experiencing.

cchambers,

I'm thinking along the same lines you are. Surge on reapplying power. But it shouldn't cause a problem, under normal circumstances. Are you using STEEL din rail? Is your grounding up to snuff?