> Where can I download library for Modbus TCP communication PLC Moeller XC-CPU 201?
For simple read and writing of data, you might consider https://www.ruby-toolbox.com/projects/modbus-cli
This will allow you to check the connection and exchange data quite simply.
The rmodbus library may be used as a 'driver' for your own scripts.
All of it open source based on ruby, runs on any platform.