ProgLogConfuser

Sorry about that, I don't have notifications setup right and didn't see anyone had responded. Yes, I am talking about programmatically changing I/O target IP.   I figured it's 'not possible' but thought I'd get a 2nd opinion.  Thanks!  

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!