4 Relay, 4 Input Expansion Module
The X-17s™ expansion module is used in conjunction with the X-400 or X-600M™ controller. The X-17s is a multi-function module with four relays and four optically-isolated digital inputs.
One or more X-17s expansion modules can be connected to an X-400 or X-600M controller with a ribbon cable which provides both power and communications.
More information is available on the website of ControlByWeb.