Modbus Interface 4-2
© 2012 HMS Industrial Networks AB
Doc.Id. HMSI-168-25
Supported Modbus Functions
The Modbus function codes supported by the Modbus interface are listed in the
table below.
Function
Code
Name
Description
1
Read Coil Status
Read the state of 1 or more bits in the Output
table.
2
Read Input
Status
Read the state of 1 or more bits in the Input
table.
3
Read Holding
Registers
Read the value of 1 or more words from the
Output table.
4
Read Input
Registers
Read the value of 1 or more words from the
Input table.
5
Force Single
Coil
Set the state of a single bit in the Output table.
6
Preset Single
Register
Set the value of a single word in the Output
table.
7
Read Exception
Status
Read the exception status register. See “Excep-
tion Status Register” on page 4-3.
8
Diagnostics
Diagnostic functions. See “Diagnostic Sub-
functions” on page 4-3.
15
Force Multiple
Coils
Set the state of 1 or more bits in the Output
table.
16
Preset Multiple
Registers
Set the value of 1 or more words in the Output
table.
22
Mask Write
Register
Set the value of a word in the Output table
based on the AND and OR Mask provided.
The register is set using the following formula:
Table 4-1 Supported Modbus Function Codes
Reg ANDMask
ORMask ANDMask