How to connect arduino to plc schneider m221 hardware via rs232

[Anonymous user]

I want to communicate from arduino to plc via rs232. I have made settings on the arduino and with the help of the modbus tester it is known that "Read Ok" means that the data has been sent from the arduino. However, after setting up the PLC m221 machine basic expert via a serial line modbus IO scanner with the slave address and offset that has been set but the value for %iwn when commissioning is an error or is red. Based on the error code from %iwns100 the error is because "Device not scanned correctly due to a communication error detected on a channel of the
device." Do you have any suggestions on how to make random values ​​generated in the Arduino program read in the PLC program? thankyou