It is currently implemented using: TCP/IP over Ethernet. MODBUS is an application layer messaging protocol for client/server communication between devices connected on different types of buses or networks. The objective of this document is to describe the function codes used within the framework of MODBUS transactions. MODBUS function codes are elements of MODBUS request/reply PDUs. MODBUS is a request/reply protocol and offers services specified by function codes. The Internet community can access MODBUS at a reserved system port 502 on the TCP/IP stack. Today, support for the simple and elegant structure of MODBUS continues to grow. The industry s serial de facto standard since 1979, MODBUS continues to enable millions of automation devices to communicate.
Is modbus a form of serial communication protocol code#
1 MODBUS APPLICATION PROTOCOL SPECIFICATION V1.1b CONTENTS 1 Introduction Scope of this document Abbreviations Context General description Protocol description Data Encoding MODBUS Data model MODBUS Addressing model Define MODBUS Transaction Function Code Categories Public Function Code Definition Function codes descriptions (0x01) Read Coils (0x02) Read Discrete Inputs (0x03) Read Holding Registers (0x04) Read Input Registers (0x05) Write Single Coil (0x06) Write Single Register (0x07) Read Exception Status (Serial Line only) (0x08) Diagnostics (Serial Line only) Sub-function codes supported by the serial line devices Example and state diagram (0x0B) Get Comm Event Counter (Serial Line only) (0x0C) Get Comm Event Log (Serial Line only) (0x0F) Write Multiple Coils (0x10) Write Multiple registers (0x11) Report Slave ID (Serial Line only) (0x14) Read File Record (0x15) Write File Record (0x16) Mask Write Register (0x17) Read/Write Multiple registers (0x18) Read FIFO Queue ( 0x2B) Encapsulated Interface Transport / 13 (0x2B / 0x0D) CANopen General Reference and PDU / 14 (0x2B / 0x0E) Read Device Identification MODBUS Exception s.48 Annex A (Informative): MODBUS RESERVED FUNCTION CODES, SUBCODES AND MEI TYPES.51 Annex B (Informative): CAPEN GENERAL REFERENCE COMMAND.51 December 28, /51Ģ 1 Introduction 1.1 Scope of this document MODBUS is an application layer messaging protocol, positioned at level 7 of the OSI model, that provides client/server communication between devices connected on different types of buses or networks.
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