Appendix A. Modbus reference
A.1 Communication settings
The following table lists the default Modbus serial settings of devices ordered with the Modbus
configuration option.
Table 38 Modbus communication settings
Property
Description/Value
Serial bit rate
19200
Parity
None
Number of data bits
8
Number of stop bits
2
Flow control
None
Modbus device address
240
Serial delay
0
Communication mode
Modbus RTU
You can use up to 32 probes on the same RS-485 line when the communication speed is
19200 bps or lower. You must configure each probe on the line to have a different Modbus
address.
RS-485 termination must not be used with HMP60/HMP110 series probes.
After power-up, it may take up to 2 seconds before the probe responds to any
Modbus request.
A.2 Function codes
Table 39 Supported Modbus function codes
Function code
Function code (hexadecimal)
Name
03
03
hex
Read Holding Registers
16
10
hex
Write Multiple Registers
Appendix A – Modbus reference
85