The Modbus variant used in GMW87 is Modbus RTU. For a list of the Modbus registers available in GMW87, see Modbus registers.
You can use up to 8 transmitters on the same RS-485 line. You must configure each transmitter on the line to have a different Modbus address.
Before taking the transmitter into use, check that the Modbus device address, bit rate setting, and parity setting match the settings in your system.
The number of stop bits is not significant. The device supports automatically both 1 and 2 stop bits.
Make selections with the DIP switches by sliding the DIP switch to the right (ON). Keep the other DIP switches on the left position (OFF).
Setting Modbus device address with DIP switches
Modbus device address ranges
The Modbus device address range for the transmitter is 1 … 247. Up to 255 is possible, but non-standard.
If no address is selected (0), the device is off-line and will not respond to any Modbus requests.