There are at least a couple options you have. You can use the host name if DHCP registers new assignments with DNS. Or you could use a static address. If you can’t/don’t want to change the PLC configuration, you can have DHCP assign the same IP address to the PLC every time. DHCP uses the MAC address of the PLC to dynamically assign the static IP address. The MAC address should be labeled somewhere on the PLC (or in the PLC configuration somewhere). If no label is found you can look at the ARP table on your PC (or the PLC’s gateway if routing is involved). Hope this helps.