How to Test an FP-DO-403

[wd8ivl]

Hello All!

I have two identical test cells with PC's, FP I/O modules and a DMM.  They use the same test software, IAK files, etc, from the network (the FP I/O is connected to the PCs via a second NIC in the PC, and not over the plant network).  Each cell uses an FP-DO-403 to control relays to route signals to DMM.

In one of the cells, I believe I'm having an occasional problem with more than one of the relays controlled by the DO-403 being closed at a time - basically backfeeding one measurement point to another.  This has never been a problem with the other test cell.  

Is there a way for me to test the DO-403 to see if it's turning it's outputs on, and especially off, in the time specified?

Thanks,

Mike

[Ryan_V[DE]]

Mike,

I suspect that if the DO-403 is working at all, then it is working correctly. Are you switching both relays with a single FP Write? Would it be a possiblity to switch one relay off, then the other on?  If you are switching them at the same time, I suspect that variation in the time it takes the relays to switch is the cause of the problem. This is a mechanical phenomenon, which is much slower than the time it takes for a transistor to turn on. I would recommend using two FP Writes to eliminate this issue.

Hope this helps,