Checking Ethernet Comm status

Processor: Modicon 140 CPU 652 60
Ethernet Card: 140 NOC 771 01
Device: Eaton C441R


I have set up a starter using the Eaton C441R attached to the OL block. If the starter is ON and I unplug the Ethernet cable (to simulate network failure) the starter will switch OFF. However, when the cable is plugged back up the starter pulls back in. I need the starter to stay OFF after a communication failure.

How can I program this?



I have tried to use the "Comms Failed" fault bit, but it chatters (quickly on/off) the starter upon reestablishing communications. I assume this is due to it taking a scan to update the bits.

I'm thinking of some kind of timer ran test - every 500ms or so it checks to see if it can still communicate. If not, it sets a bit that I can use in the logic to turn off the output. I just don't know where to have it look...

Is this ModbusTCP with IOScanner or EtherNet/IP class 1 I/O communications?

How exactly are you using the fault bits? With ModbusTCP, the fault bit indicates an error condition when no new data is received within the health timeout period. So if you pull the cable, the bit should indicate error, then if this is caught and used to reset the output value (assume set a zero to some word or bit that gets transferred to device?).

With EtherNet/IP, the process is similar, except I believe the fault bit indicates that an EIP timeout has occurred, which can be configured for each connection in the NOC module DTM.

I would expect that on startup of the connection, this off state is then transferred. I would think link up/down event to take more than one scan unless you are running periodic in the 100's of ms range. What is your scan time?