MODBUS TCP Read Multiple Registers?

[klikopc]

Hi!

Can anyone help me with ModBus TCP Read Multiple Registers(Function Code 03)?

I have a Master Request:
00 00 00 00 00 06 01 03 64 06 00 07

Can anyone tell me what the response looks like(lets assume that all registers have a value of 9)?

Thanks

 

[cjh]

It would look like this:

00 00 00 00 00 11 01 03 0e 00 09 00 09 00 09 00 09 00 09 00 09 00 09

Explanation:

00 = Transaction ID High byte
00 = Transaction ID Low byte
00 = Protocol ID High byte (always 0)
00 = Protocol ID Low byte (always 0)
00 = Length of bytes following High byte
11 = Length of bytes following Low byte
01 = Unit Identifier
03 = Function Code (03: Read Holding Registers)
0e = Size of data returned
00 = First data register High byte
09 = First data register Low byte
00 = Second data register High byte
09 = Second data register Low byte
Etc...

 

[klikopc]

Thanks cjh, it works!