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What is "Modbus"?

This commands give you the possibility to control the relays on a R6 extension module via a modbus command send as a hex-file in a tcp stack.

It is easy to connect the R6 extension module to the RS485 interface of a Barix device. You have to wire Pin6 (A) and Pin9 (B) of the DB9 connector to Pin2 (A) and Pin3 (B) of the J1 connector on the R6 extension module.

Additional you have to power up the R6 extension module on Pin4 (+) and Pin5 (-) on J1 connector with an external power supply.

The serial settings for the RS485 interface (Serial 2) should set to a baudrate of 19200 Bd, a data bitrate of 8 bits, parity set to even, 1 stopbit, handshake set to RS485 direction control and the local port to 502.

Now it is possible to send a hex-file, which includes the modbus command, via tcp to port 502 of the Barix device. This can be done with the NetCat Application (nc -q 1 ip-barix port < filename).

The table shows the modbus commands to control the relays on a R6 extension module:

-Modbus Address--Single Coil--Address HI--Address LO--Values HI--Values LO--CRC LO--CRC HI-

-Relay 1-


-Relay 2-




-Relay 3-


-Relay 4-


-Relay 5-


-Relay 6-


Please note: It is necessary to calculate a crc-check-sum for each command and add it to the command itself.

Here you can find a online crc-calculator:

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