Appendix A. Modbus reference
A.1 Default communication settings
Table 15 Default 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
You can use up to ten devices on the same RS-485 line. You must configure each device on the
line to have a different Modbus address.
A.2 Function codes
Table 16 Modbus function codes
Function code
Function code (hexadecimal)
Name
03
03
hex
Read Holding Registers
16
10
hex
Write Multiple Registers
43 / 14
2B
hex
/ 0E
hex
Read Device Identification
A.3 Data encoding
In the data registers, the numeric values are available in one or two formats with separate
register addresses: 32-bit IEEE floating point format and/or 16-bit signed integer format.
For values that have both 32-bit and 16-bit register available, use of the 32-bit
register is recommended. Some values may exceed the signed 16-bit range even
in normal operation.
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