Modbus Tcp/Ip; Modbus Function Codes; Modbus Exception Codes; Modbus Tcp/Ip Gateway Behaviour - ISE smart connect Modbus Vaillant Product Manual

4

Modbus TCP/IP

4.1

Modbus function codes

The following function codes are supported via Modbus TCP/IP:
Function Hex
code
03 0x03
04 0x04
06 0x06
16 0x10
4.2

Modbus exception codes

The following exception codes can be generated by the gateway:
Exception Hex
code
01 0x01
02 0x02
03 0x03
04 0x04
11 0x0B
4.3

Modbus TCP/IP Gateway behaviour


All addresses are one-based. If you request register 1, you get the value of register 1.

For 32-bit data points, the first register contains the least significant word.

32-bit data points (two registers) can only be written contiguously with function code 0x10 (Write
Multiple Registers). Write requests, which try to set only 16-bit (one register) of a 32-bit data
point (two registers) are responded with exception code 0x02 (Illegal Data Address).

Requests to non-existing/inactive unit IDs are responded with exception code 0x0B (Gateway
Target Device Failed To Respond).
Order No. S-0002-007
Name
Read Holding Registers
Read Input Registers
Write Single Register
Write Multiple Registers
Name
Illegal Function Code
Illegal Data Address
Illegal Data Value
Server Failure
Gateway Target
Device Failed To
Respond
ise smart connect Modbus Vaillant
Description
The function code is unknown to the server
Data Address not accessible (dependant on the request)
Data Value not supported (dependant on the request)
The server failed during the execution
Indicates that no response was obtained from the target
device (unit ID).
Usually means that the device (unit ID) is not present on
the network.
Modbus TCP/IP
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