Tyco XI800 Interface Module is used in conjunction with a galvanic isolator to provide a path for a compatible MX Control and Indicating Equipment (c.i.e.) to transparently communicate to compatible devices connected to an Intrinsically Safe (I.S.) spur. The interface reduces the standard MX loop supply voltage and signalling currents to levels that are acceptable for I.S. devices operating in hazardous areas. It converts the low-level reply messages from the slave devices on the I.S. spur, in order to be compatible with the standard MX digital protocol. The EXI800 electronics is fitted into a DIN rail mounted housing.