User`s manual

6-11
6.5 MODBUS Communication Protocol
INP-TN5A0202-E
Function code
With MODBUS protocol, the different coil number/register number is allocated depends on the function code, and each function
code is only available for a certain coil number/register number.
The diagram below is shown the correspondence between the function code and the coil number/register number.
Function code Coil / Register No.
Code Function Target No. Contents
03H Read out (continuous) Hold register 3xxxx Read out word data
04H Read out (continuous) Input register 4xxxx Read out/Write word data
06H Write Hold register
10H Write (continuous) Hold register
The message length on the each function is shown below.
Code Contents
Number of
allocatable data
Command message Response message
Minimum Maximum Minimum Maximum
03H Read word data 125 words* 8 bytes 8 bytes 7 bytes 69 bytes
04H
Read out word data (Read out
only)
125 words* 8 bytes 8 bytes 7 bytes 69 bytes
06H Write word data 1 word 8 bytes 8 bytes 8 bytes 8 bytes
10H Write series of word data 123 words* 11 bytes 73 bytes 8 bytes 8 bytes
*: “Number of allocatable data” above is limited by the number of data that the equipment allocates for the coil/address number.
(Excluding the function code 06H)