GMM-MMI is the Interface Module for Gas and Moisture Monitor’s (GMP) installation in the panel. It communicates with the GMP – Periscope module via RS485 port and provides on-site information on its front displays, and remotely via 2 analog outputs in current loop, configurable by software for indications of hydrogen concentration, relative humidity, oil temperature and water content. It is provided with 2 serial communication ports: one RS 232 for local connection with laptop computer and one RS 485 for connection with the supervision system. It is equipped with 7 contacts for signaling of alarms configurable as NO or NC, and one NC contact for indication of internal errors (self-diagnostic) or power outage. It is provided with internal clock and mass memory for storage of measurements and alarms occurred.