Hi Everybody

I would like to change IP address of my CPU compact logix PLC. Problem is that ethernet port of CPU communicates with 6 FLEX I/Os. Will I need change Flex I/O IP's as well to leave system running OK?

 

It depends. Let's say, for example, your CompactLogix and your Flex I/O are all on the 192.168.1.x subnet. If you want to change your CompactLogix from 192.168.1.3 to 192.168.1.200, no problem. If you want to change to 10.10.10.10, then yes, you will need to change the Flex I/O to the 10.10.10.x subnet.

It gets more complicated than this. But generally speaking on a simple network like this all of your devices have to be on the same subnet.

-James Ingraham
Sage Automation, Inc.

 

I agree entirely with James' comment.

We always install 2 Ethernet modules whenever possible. One for the I/O and HMI's and another on a different sub net for comms with the plant network.

Other options can include using a managed switch in the mix. Suggest you have a good conversation with an "INDUSTRIAL Ethernet" guy.

 

I also agree with the first answer. First ask yourselves a question - why do i need to change the address for a CPU?

Secondly - write down all the IP addresses of Flex IOs & CPU at a single place. Check the sub nets for each of the system. If already the system is connected & running fine, you should not have any problems & they should be belonging to the same subnet (unless you have major communication issues with the network).

If you are still bent on changing the IP addresses - Please ensure that you have the first 3 subnet addresses same for all the ethernet ports. (eg - 10.10.231.x1, 10.10.231.x2, 10.10.231.x3 etc). For the easy remembrance, number them 1, 2, 3, 4, 5, 6 respectively.

Good luck!