To change the IP address of your Z-series product, once logged in to the web-based user interface, you will need to click on Settings at the top, then click the Network tab on the Settings page.
From there, you can change the IP Address and Subnet Mask, which are the minimum required. You can also change the Default Gateway and the DNS Servers.
For the ACU-Z1
You will also need to verify the IP addresses for each of the modules in the chassis. On the same page identified above, you will have a section titled Card Network Settings. Here, once you've defined the ACU-Z1's IP address, you can click Generate IP addresses and the system will auto-populate the IP addresses of the modules, skipping one digit from the ACU-Z1 (i.e. if the ACU-Z1 is 192.168.1.200, the modules will be addressed to 192.168.1.202, 192.168.1.203, 192.168.1.204...). Alternatively, you can designate the IP addresses for each module manually.
NOTE: The modules MUST be on the same network/subnet as the ACU-Z1. They will use the same Subnet Mask, Default Gateway, and DNS Servers as the ACU-Z1. 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.