Hi

I have a problem getting Modbus data from a device using Modbus TCP with the built in MB_CLIENT in TIA portal on a S7-1516 PLC. The status of the connection swopps between 7005 (Data is being sent), 7006 (Data is being received), and 8383 (Error reading or writing data or access outside the address area of MB_DATA_PTR). I have tried the same connection with a Modbus test program (QModMaster), and this works fine.

For my setup, the device I'm connected to has IP 10.0.0.29, TCP port 502, unit ID 1. I'm using function code 4 (Read input registers), start address of 4100 (new standard address format) and read 68 registers. This is a register area allowed for reading data. As you can see in the attached picture, this works fine with the test program.

For my MB_CLIENT for the PLC I use Mode 104, MB_DATA_ADDR 44120, and access 2 registers for the test. Here I have tried multiple different settings without any luck.

Do anybody have any tip to help me?

Best Ole Eivind