Setting Modbus device address with DIP switches
Figure 6 Modbus device address DIP switch
example
DIP
switches 32,
8, and 1 set
to ON
The Modbus device address
is encoded in eight bit
binary form, with each
numbered switch
representing a single bit.
This example shows
address 41 selected: DIP
switches 32, 8, and 1
(decimal: 41, binary:
00101001) are set to ON.
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.
Troubleshooting
If you experience problems with GMW87M, first see the following table concerning the behavior and
error indications of the transmitter.
Table 1 Troubleshooting table
Problem
Solution
The device is not responding
• Power-cycle the transmitter by disconnecting the screw
terminal block
• Check power supply voltage
• Check wiring, including RS-485 bus polarity
• Check that RS GND is connected between the transmitter and
the receiver
• Compare the DIP switch settings to your Modbus host settings
• Check that RS-485 termination is enabled only on the last
device of the wiring
• Alternatively, try operation without RS-485 termination at all
Unexpected value in Modbus
response
• Change register number and/or data encoding settings in your
Modbus host system
No measurement result and/or
non-zero status code returned
• Device is warming up, try again after 20 seconds
• Power-cycle the transmitter by disconnecting the screw
terminal block
• Check that the GM10 module is properly attached
• Contact Vaisala for a replacement GM10 module
If you cannot locate the source of the error and return the transmitter to operational state,
contact Vaisala technical support. See
.
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M212445EN-A
