I have a 2 CompactLogix PLCs running right now, communicating CIP Safety and Standard data over Ethernet I/P. For reasons I can't explain right now, the IP address of the second one HAS TO change semi-randomly (the 1st PLC is static). Setting the 2nd PLC's IP to static or assigning it a static DHCP address is the obvious solution, but for the purpose of this question, that cannot be done.
Is there a way to programmatically change its IP address on the 1st PLC's program? (There is an HMI attached to the 1st PLC and adding a screen to enter in the new address would be trivial.) The only bit I'm still missing is how do I change the IP address on the module in the 1st PLC so that it's pointed at the right IP address of the 2nd one when it changes. I found instructions on how to use msg instructions, but that hasn't worked yet. Any help would be appreciated.
Thanks!