The transmitter conveys its sensor signal over two wires. Use a two-conductor shielded cable
for each transmitter in the system. As with the input power connections, color-coded wires exit
the transmitter housing through the top conduit fitting so removal of the front cover should not
be necessary. At each transmitter, the positive conductor connects to the red wire and the
reference conductor connects to the green wire.
See figure 1 on page 16 for a wiring diagram.
Connecting the Modbus Output
The Brasch Gas Transmitters also include a circuit that provides digital communication via
Modbus RTU protocol. This output allows a client device to read the firmware version, gas
sensor type, gas sensor value, and any error codes associated with the transmitter. Color-
coded wires exit the transmitter housing through the top conduit fitting so removal of the front
cover should not be necessary. At each transmitter, the positive conductor connects to the
brown wire and the negative conductor connects to the blue wire.
See figure 2 on page 16 for a wiring diagram. A more complete description, including
instructions on setting up the client, is available in the dedicated Modbus Setup Guide.
Applying Power For the First Time
Once all the wiring connections are complete, the transmitter is ready for power to be applied.
The green power LED will glow immediately and the output will begin transmitting. However,
the first 2.5 minutes after the power is applied should be considered a warm-up period as the
sensor readings will not be fully stabilized yet. After this time, the transmitter is ready to
monitor the area for target gas.
IOM02
Rev 1.0 – December 22, 2020
15
