Liquiline CM44x Modbus Guideline V1.0
Hauser
8
© Copyright Dez. 2011
3.2.1.
FC03 Read Holding Register
This function reads one or several holding registers. Up to 125 successional registers can be read.
Request
Function code
1 Byte
0x03
Starting Address
2 Bytes
0x0000 to 0xFFFF
Quantity of Registers
2 Bytes
1 to 125 (0x7D)
Response
Function code
1 Byte
0x03
Byte count
1 Bytes
2 * Quantity of registers
Holding register value
(2 * Quantity of registers) Bytes
2 to 250
Error
Error code
1 Byte
0x83
Exception code
1 Bytes
01 or 02 or 03 or 04
3.2.2.
FC04 Read Input Register
This function code is used to read one or several input registers. Up to 125 successional registers can be read.
Request
Function code
1 Byte
0x04
Starting Address
2 Bytes
0x0000 to 0xFFFF
Quantity of Registers
2 Bytes
1 to 125 (0x7D)
Response
Function code
1 Byte
0x04
Byte count
1 Bytes
2 * Quantity of registers
Input register value
(2 * Quantity of registers) Bytes
2 to 250
Error
Error code
1 Byte
0x84
Exception code
1 Bytes
01 or 02 or 03 or 04
3.2.3.
FC08 Diagnostics (nur seriell)
This function code is used to test the Modbus communication between the client (master) and the server (slave)
and to check for various error conditions within the server. Sending not supported sub-function codes cause an
ILLEGAL DATA VALUE response.
Function code
1 Byte
0x06
Sub-function
2 Bytes
Data
N x 2 Bytes
Response
Function code
1 Byte
1 Byte
Sub-function
2 Bytes
Data
N x 2 Bytes