About PROFIBUS: communication backbone network of production plant

One PROFIBUS What is it? ？

PROFIBUS standard existing 20 Years of history , It is a mature digital Fieldbus Technology , Used in many factory and process automation applications , And food 、 Mixed industries such as beverages and pharmaceuticals . according to PROFIBUS and PROFINET The international （PI） association The data of ,2015 year PROFIBUS The sales volume of equipment exceeds 5000 Ten thousand units , And that number is still growing . Next, let's have a deeper understanding of PROFIBUS, What it is and how it works .

PROFIBUS Is the abbreviation of process fieldbus , In the field of automation technology, it is regarded as one of the main fieldbus communication standards .PROFIBUS Support the use of a single bus cable for digital data exchange in the network . at present , It has two variants , What is commonly used is PROFIBUS DP（ Distributed peripherals ）, It is used to operate sensors and actuators through a centralized controller .

PROFIBUS Usually use EIA-485 Transmission technology as its physical layer . Based on a pair with 150 Shielded copper cable of twisted pair with ohmic impedance ,EIA-485 Support will be up to 126 Sites are connected to one PROFIBUS DP The Internet , It also supports linear bus topology . Fieldbus data link （FDL） The agreement defines PROFIBUS Data link layer . Through token passing ,FDL Define network access and distinguish between master and slave , meanwhile , It also controls the time slots of each master station .

Two PROFIBUS DP What are the types of equipment ？

according to PROFIBUS DP agreement ,PROFIBUS DP There are three types of equipment ：

1. PROFIBUS DP 1 Class master station

This kind of control is used for the communication process of exchanging process values , Each slave station uses the defined cycle command during the configured time slot . This kind of equipment mainly includes controller and PC.

2. PROFIBUS DP 2 Class master station

This class accesses the fieldbus by using acyclic Services , So as to realize the configuration and parameterization of intelligent field equipment . Such equipment includes engineering and operation panels .

3. PROFIBUS DP From station

These peripheral devices read input information and send output information to the periphery . The upper limit of input and output data that such devices can handle is ：246 Bytes of input data and 244 Byte output data .

3、 ... and PROFIBUS What network architectures are supported ？

Based on the above equipment types ,PROFIBUS It can support different network architectures , Include ：

1. Single master network

This kind of network architecture has only one master station -PROFIBUS DP 1 Class master station —— During operation, connect to PROFIBUS DP The Internet . When the controller acts as a central control unit , Each remote slave station is connected to the fieldbus . A single master network can achieve shorter fieldbus cycle time .

2. Multi master network

This kind of network architecture has multiple master stations -PROFIBUS DP 1 Class master station and PROFIBUS DP 2 Class master station —— Connect to PROFIBUS DP The Internet , Build an independent subnet . Each subnet consists of a 1 Class master station equipment and appropriate slave stations , Or they can also contain additional stations for development and diagnostics . Although all master stations can read the input and output values of slave stations , But only those configured for the slave 1 Class master can write the output value of slave .

Four How to diagnose PROFIBUS The Internet ？

because PROFIBUS It's a maturity 、 Robust technology , Therefore, the cause of any failure is usually not a deep-seated technical problem . contrary , Potential problems are usually connector failures or incorrect bus terminals . even so , It's not always easy to find the root cause of wrong behavior , for example ,PROFIBUS Communication may only fail occasionally , And in the whole network , You may also detect errors in seemingly unrelated parts .

To help you detect PROFIBUS fault , Some tools provide a wide range of functions —— For cable testing 、 Electrical signal analysis and logical network analysis . For more information about troubleshooting equipment and PROFIBUS Good practice , Please visit our PROFIBUS Tester 5 Product page .

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