ModbusRTUlib libraryTXV 003 52

The ModbusRTUlib library contains declarations of functions, function blocks, data types and global variables for Modbus master communication. The ModbusRTUlib library uses some functions from the ComLib and CrcLib libraries.
The library is delivered as a part of the installation of the Mosaic environment from version v 2.0.25.0. ModbusRTUlib library functions and function blocks are supported in K-series central units (TC700 CP-7004 and all Foxtrot system variants) from version v 5.7. and higher.

Modbus RTU is an open serial protocol published by Modicon as early as 1979. The Modbus standard is defined as an application layer in the 7-level OSI model that performs "Client / Server" communication between two devices connected by different types of buses or communication networks. On serial lines, the protocol exchanges data between one master station and one or more slave stations at a time. This means that one station controls the communication and the other stations answer the questions.

The variant for Ethernet is called Modbus TCP. It has its port number 502 reserved in Ethernet networks. The principle of data transmission and communication functions are the same as for Modbus RTU. In Ethernet networks, communication can take place simultaneously between multiple clients and multiple servers at once.

The ModbusRTUlib library allows to implement communication in both modes, ie PLC Tecomat in the role of server (slave) or client (master).