Modbus RJ12 Wiring

The RJ12 port connector is located between the SD card and USB slots. The connector provides Modbus bus wires, ground potential G0, and power supply directly connected to G terminal from the power supply connector (the external devices can be powered through the RJ12 connector). A wiring diagram is shown in the figure below.

Modbus RJ12 wiring

The RJ12 pins description:

Pin1: G0 potential, (SD card side);
Pin2: RS485 - (B);
Pin3: RS485 + (A);
Pin4: G0 potential;
Pin5: G potential, directly connected to G terminal in power supply;
Pin6: G potential, directly connected to G terminal in power supply (USB side).

Connection of the devices is shown in the figure below.

RJ12 to RS485 Modbus connection