Profibus Basic Knowledge Learning--Message

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Profibus DP Simple introduction of communication protocols

First, the Profibus DP Communication protocol is a single, consistent communication protocol for all plant automation and process automation.

This protocol uses "master-slave" mode: one Device (master) controls one or more other devices (from);

Protocol use: "token" mode: "token" is passed through the network, the station with the token control has access to the network.

Profibus DP exists in three versions:

DP-V0:OVERALL command structure cyclic data exchange

DP-V1: Extended to non-cyclic data exchange, etc.

DP-V2: Further expansion to timely, clock synchronization and so on.

A single protocol that adapts to all applications

Profibus DP supports all DCs or controllers with a single field device;

Plant equipment and process equipment are directly connected to the Profibus DP;

Process automation equipment (PA), aggregated in the "PA cluster", connected to the Profibus DP via a connector or chain ring;

The Profibus Bus Access Protocol (second tier) is the same for three versions of Profibus (FMS/DP/PA);

This makes communication transparent and FMS/DP/PA network area easy to combine;

Because the FMS/DP uses the same physical media (RS-485/FO), they can be combined on the same cable.

Ii. Characteristics of profibus-Bus Access Protocol

Hybrid Bus Access Protocol:

Logical token ring between main stations

Master-Slave protocol between master and slave stations

Main station:

The active station has control over the bus for a limited period (Token hold time).

From Station:

Slave just responds to a request from a master, they have no control over the bus.

Iii. features of the profibus-Bus Access Protocol (FDL)

The master or slave can be connected or disconnected at any point in time, and the FDL will automatically reorganize the token ring;

Token scheduling ensures that each master has sufficient time to perform its communication tasks, so that the user must calculate the time of the entire target token ring;

The bus access Protocol has the ability to detect faulty stations, failed tokens, duplicate tokens, transmission errors, and all other possible network failures.

All information, including token information, ensures a high level of security during the transfer process to avoid transmission errors. Hamming distance hd=4.

Four, profibus-token scheduling principle

In a multi-master network, token scheduling must ensure that each master has sufficient time to complete his communication tasks;

The user organizes all target token cycle times (TTR) into the communication task account of all master stations;

Each master station calculates the time it takes to complete its communication task after receiving the token, based on the following formula (TTH):


Tth= time to hold the token

Ttr= Target Token cycle time

trr= Actual token cycle time

V. Structure of the PROFIBUS message

Vi. Crawling of network messages

The crawl and analysis of all the communication messages in the network communication is an important work, how to crawl the data packets of communication in Profibus bus network, and how to analyze them? PROFIBUS TESTER 5 helps you solve this problem, he can not only carry on the basic physical layer of the network test, including cable short circuit, circuit breaker, cross, shielding layer breakage, signal waveform, level, Snr and so on, but also can crawl all the messages, analyze the message, the message is detailed analysis, Easy for your analysis. This is a very high cost-effective products, I use a very good, need to contact me [email protected]

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Profibus Basic Knowledge Learning--Message

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