CLX comms to ML1400 recovery after disconnect

[theDave2]

We've got a CLX L35E (v16.3)sending/receiving data to a MicroLogix 1400, via MSG instruction over ethernet. We read then write data every second.

We are using CIP communication method with SLC Typed Reads and Writes, to N100 in the ML1400.

What we see is that when we turn power off the ML1400 and then back on, the MSG block takes 7 minutes to recover and communicate again.

The MSG block does give the ER bit and error code for comm time out. We allow 10 seconds after the ER bit before we try again. We don't keep the MSG block energized all the time when reading/writing as we just look for the DN or ER bit to be set as it's sequential stepping logic for the code.

Any thoughts ? Should we be using CIP w/source id ? If so, where is that explained ? How about keeping power flow into the MSG block until we see the DN or ER bit ?

Thanks,
Dave

 

[Ken Roach]

I suspect it's a TCP Keepalive issue.

Is the MicroLogix 1400 shutdown time very short ? Experiment by leaving the controller off for 30 seconds, then try 60 seconds.

I suspect that the CIP connection is timing out, but the TCP connection isn't. I don't know if there's a way to cancel the TCP connection on the ControlLogix side without rebooting the 1756-ENBT.

This is a job for Wireshark.....

 

[theDave2]

That's a good point.

Typically, the operators shut down the ML1400 from 30 sec. to 5 min. to clear a jam.

Us engineers, for checking this problem, turn it off for only 30 sec.

We'll leave it off for longer times to check if it's the TCP.

Re-booting the CLX does take care of the problem, but that's not a viable solution.