1756-ENET /A Issues

Our plant has been shutdown since Christmas and we are getting ready to restart it. We have a fairly large Ethernet network and I began to restart everything , check the network , etc. I have a ControlLogix rack with a 1756-ENET/A Ethernet module. Everything on the card looked fine ,until I turned on the server pc with RS View SE.Once the application came up , I was polling data from the 1756-ENET for about 5 seconds and then the 1756-ENET would fault out with…….Duplicate IP 00:00:BC:31:13:C8LED’s are as follows….Net – Red SteadyOK- Flash RedLink - Green SteadyIn this state I cannot ping my IP address 192.168.100.4But when the card is in the correct state I can ping that IP address with no problems. I searched for a dedicated manual for the 1756-ENET but get the 1756-ENBT.Do you have any suggestions,Thanks in advance.

Sounds like there is another device on the network with that IP Address. When this happens can you unplug the ENET card and still ping the IP? You maybe have to track down which device that is, might be harder if anything has reset to defaults or is getting it's address from DHCP.

The 1756-ENET is the older 10 MB-only Ethernet module for ControlLogix. Those did not have a scrolling dot-matrix display, only a couple of Status LEDs, so the best way to view their configuration was to browse using RSLinx and another path to the backplane (often through DH+ or even the controller serial port).

I agree that you definitely have a duplicate IP situation. Finding duplicate IP's is a standard IT department troubleshooting exercise, often using PING and ARP commands from the command line.

Thanks , your right. I unplugged the cable on the 1756-ENET/A 192.168.100.4 and pinged it again and it found another 192.168.100.4 Everything was fine when we shut down at Christmas. I can't imagine that when I powered everything back up , a 192.168.100.4 landed someplace.I will look again tomorrow. Thanks for your help.

Are the addresses handed out by DHCP? If so you may want to set a reservation for each iP address by MAC ID so it only gets handed out to the correct device and gets taken out of the open pool.

Thanks for your help. It was a Panelview Plus 700 that some way recieved the same IP Address. One that we hardly use.

Thanks again.