SE Modicon M580 Brochure

Modicon M580 automation platform Industrial Ethernet services Modicon M580 communication services

Functions (continued)

Functions (continued) Modbus standard communication protocol

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Modbus, the industry communication standard since 1979, has been combined with Ethernet Modbus/TCP, the medium for the Internet revolution, to form Modbus/TCP, a completely open Ethernet protocol. The development of a connection to Modbus/ TCP does not require any proprietary component, nor purchase of a license. This protocol can easily be combined with any product supporting a standard TCP/ IP communication stack. The specifications can be obtained free of charge from The Modbus application layer is very simple and universally familiar with its 9 million installed connections. Thousands of manufacturers have already implemented this protocol. Many have already developed a Modbus/TCP connection and numerous products are currently available. The simplicity of Modbus/TCP enables any field device, such as an I/O module, to communicate on Ethernet without the need for a powerful microprocessor or a lot of internal memory. Modbus/TCP, high performance Due to the simplicity of its protocol and the fast speed of 100 Mbps Ethernet, the performance of Modbus/TCP is excellent. This allows this type of network to be used in real-time applications such as I/O scanning. Modbus/TCP, a standard The application protocol is identical on Modbus serial link, Modbus Plus, or Modbus/TCP. This means that messages can be routed from one network to the other without converting protocol. Since Modbus is implemented on top of the TCP/IP layer, users can also benefit from IP routing enabling devices located anywhere in the world to communicate without worrying about the distance between them. Schneider Electric offers a complete range of gateways for interconnecting a Modbus/TCP network to existing Modbus Plus or Modbus serial link networks. The IANA organization (Internet Assigned Numbers Authority) has allocated the fixed port TCP 502 (well-known port) to the Modbus protocol. Thus Modbus has become an Internet standard. Modbus and Modbus/TCP are recognized by the IEC/EN 61158 international standard as a fieldbus. They are also compliant with the “Chinese National Standard” managed by ITEI. Interfacing CANopen with Modbus/TCP CiA DSP 309-2 provides standardized mapping of CANopen data for transport on Ethernet Modbus/TCP networks. The specification reserves Modbus function code 43/13 for this purpose. This function code is reserved exclusively for CANopen. Modbus TCP/IP characteristics Maximum size of data: Modbus Organization website. Modbus/TCP, simple and open

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Modbus/TCP function codes

dec hex

Bit access

Read n input bits Read n output bits

02 01 07 05 15 04 03 06 16

02 01 07 05 0F 04 03 06 10

Read exception status Write 1 output bit Write n output bits Read 1 input word Read n input words Write 1 output word Write n output words

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Read device ID

43/14 2B/0E

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Examples of Modbus/TCP function codes for accessing data and diagnostics

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b Read: 125 words or registers b Write: 100 words or registers

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Processors: page 2/2

I/O architectures: page 5/2

Modules for severe environments: page 6/2

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