The device is equipped with two parallel sockets with the same pin configuration. These sockets provide communication via the Modbus RTU protocol. The communication pins are internally connected with the main RS485 interface and they have the same functionality. RJ12 sockets are designed for providing an easy connection with devices such as iSMA-B-FCU or iSMA-B-LP.

The RJ12 socket can also transfer power supply through the pins no. 4, 5, and 6, which are internally connected, for example, with the iSMA-B-FCU unit (see the figure below). Before connecting the devices powered from the RJ12 socket, it is necessary to calculate the power load of all the devices.

Internal connections between RJ12 sockets and a main RS485 socket

Power supply transferred over RJ12:

Connection of the iSMA-B-LP and iSMA-B-FCU with RJ12 connectors

RJ12 pins are presented in the figure below.

RJ12 pins

If the bus length is up to 100 m, it is recommended to use standard category 3, 4, or 6 wire straight telephone cable without crossing (for example, YTLYP 6x0.12).

For longer bus cables, it is recommended to use twisted shielded Modbus standard cable.