Hello everyone.
I encountered a problem reading the modbus TCP registers in Codesys.

Registers are correctly read in eg. ModbusScanner, but in Codesys I can not read any values.

I am trying to read eg. Input Register offset 100.

Due to this difficulty I can not continue the project, I am asking you for help in configuring Codesys. What to do to read anything over Modbus TCP.

I'm attaching a program file in Codesys and Arduino Uno with Ethernet Shield.

Sample of code for Arduino:

//Modbus Registers Offsets (0-9999)
const int SENSOR_IREG = 100;
//Used Pins
const int sensorPin = A0;

I will be grateful for your help, greetings. !!!

RPI1_1.project [194.35 KiB]

RPI1_1.project [194.35 KiB]

Hello. I made the same like you but with MODBUS RTU using a max485 chip to convert ttl signals to rs485 standard (plug on pins 0, 1 and 2 on arduino pcb)and the usb port from the raspberry pi. It works very well.
Maybe you have a problem with the number of register to read. I think arduino can't stor on its buffer more than 64 words.
As I told you before, my system with four arduino hanging from a raspberry pi serial port works very well, even if I turn off any arduino pcb it continues working.
BR

hello juan, thanks for yours advice!

for me, the solution was different.
I used the 28j60 ethernet shield model and there was a problem.

I bought a classic shield Ethernet "Arduino Ethernet shield R3 with micro SD connector"
like this:
https://botland.com.pl/produkty-wycofan ... crosd.html

and the connection worked!

Settings:
for input register code 4
for register 100, enter offset 0x0064 in the channel

The whole works perfectly with raspberry pi 3 B +