Introduction - If you have any usage issues, please Google them yourself
The MODBUS standard is divided into three parts. The first part ("Modbus specification") describes the MODBUS transaction. The second part ("MODBUS message transmission in the TCP/IP implementation guide") provides a help developers to implement the MODBUS application layer on the TCP/IP reference information. The third part ("MODBUS message transmission in serial link circuit implementation guide") provides a help developers to achieve the application layer of MODBUS serial link on the reference information.