MD2020 LCU

The MD2020-LCU is a Fire Alarm Loop Control Unit designed to interface with the MD2020 Control Panel and addressable devices connected on a communication line called Loop. Key features include providing power to connected devices, managing communication with up to 127 addressable devices, and acquiring information from them through an RS485 serial line. The unit includes various functional blocks such as a microprocessor, internal power supply circuit, RS485 interface, isolation surveillance circuit, and degraded operating mode interface.

The unit monitors the Loop, communicates with devices using a proprietary protocol, and signals alarms through LED indicators. In case of Loop interruption, the module continues to reach sensors, performing a full Loop scan in approximately two seconds. The microprocessor manages communication, stores Loop configuration, and activates the DEG ALARM output in case of communication absence for more than 4 seconds.

The unit operates in a degraded mode when communication with the Control Panel is interrupted for over 4 seconds, relying on sensors to transmit alarms independently. It generates a cumulative DEG-ALARM signal sent to the Control Panel through T-BUS, indicating one or more Loops in alarm without specifying the affected one(s). The unit is galvanically isolated, with monitoring circuits for Loop isolation and current measurement.

LED indicators on the unit display various states, and the DIP-SWITCH allows assigning a unique address for communication with the Control Panel. Installation is on a DIN rail using the TBUS Phoenix Contact™ connection system, supporting “Hot Swap” insertion.