To change the IP address of your Z-Series product, once logged in to the web-based user interface, you will navigate to Settings > Network at the top of the page.
From there, you can change the IP Address and Subnet Mask, which are the minimum required. You can also change the Default Gateway, the DNS Servers, and the NTP Servers.
NOTE: For the ACU-Z1 the default behavior is that each card is auto-assigned an IP address based on the IP address assigned to the CPM-Z1. They will use the same Subnet Mask, Default Gateway, DNS Servers, and NTP Servers as the CPM-Z1. You can set the cards to manually assign the IP information to them if you prefer, see the ACU-Z1 manual for more information. If the ACU-Z1 is not able to communicate with the module via IP connectivity, the module WILL NOT function.
If you don't know the current IP address of your Z-series product, you can find more information on recovering the IP address here.