ELK M1 alarm M1-XSP Lighting Serial Interface 101-214The M1XSP is a "3 in 1" product. As a lighting interface, it adapts the M1 Control to many brands of Lighting control products which use serial" communications. i. e., OnQ ALC, PCS UPB, EDT, CENTRALITY, VANTAGE, etc. As a thermostat interface, it adapts the M1 Control to HVAC Communicating Thermostats from companies such as RCS, APRILAIRE, and HAI. As a serial port expander, it expands the RS 232 communication ports of the M1 for multiple connections