The RJ12 socket is designed for connecting external modules and LCD panel. The iSMA-B-FCU device has two parallel sockets with the same pin configuration. These sockets provide communication in the Modbus RTU protocol.

The RJ12 socket provides also power supply dedicated for external LCD panels with maximum load up to 2.5 W. Before connecting devices powered from RJ12, please calculate the power supply load. Power consumption of the dedicated wall panels iSMA-B-LP with temperature sensor is 0.5 W, so the maximum number of panels on the bus is 5. The maximum number of Touch Point panels on the bus is also 5.

RJ12 pins are shown in the figure below.

RJ12 pins

For short distance, up to 100 m, it is recommended to use the following cables for connection: standard category 3-, 4-wire or 6-wire telephone cable straight without crossing (for example, YTLYP 6x0.12). For longer distance, it is recommended to use a twisted shielded Modbus standard cable.