PROFBUS is an international, open fieldbus standard suitable for both high-speed, time-critical data transmission and complex, wide-ranging communication applications. PROFBUS-DP is a communication protocol optimized for high-speed user data transmission, particularly suitable for communication between programmable logic controllers (PLCs) and fieldbus systems...
PROFBUS is an international, open fieldbus standard that can be used for both high-speed, time-critical data transmission and complex, wide-ranging communication applications.
PROFBUS-DP is a communication protocol optimized for high-speed transmission of user data, particularly suitable for communication between programmable controllers and field-distributed I/O devices.
PROFIBUS-DP is used for high-speed data transmission at the field level. The master station periodically reads input information from the slave station and periodically sends output information to the slave station. The bus cycle time must be shorter than the master station (PLC) program cycle time. In addition to periodic user data transmission, PROFIBUS-DP also provides non-periodic communication required by intelligent devices for configuration, diagnostics, and alarm handling.
Transmission technology: RS-485 twisted pair cable, double-pair cable, or fiber optic cable. Baud rate from 9.6 Kbit/s to 12 Mbit.
PROFIBUS-PA is suitable for PROFIBUS process automation. PA connects automation and process control systems to field devices such as pressure, humidity, and level transmitters. PA can replace 4-20mA analog technology. PROFIBUS-PA has the following characteristics:
(1) Industry standards suitable for process automation applications make field equipment from different manufacturers interchangeable.
(2) Adding and removing bus stations will not affect other stations, even in intrinsically secure areas.
(3) A coupler is used to connect the PROFIBUS-PA segment for process automation and the PROFIBUS-DP segment for manufacturing automation, enabling transparent communication between the two segments.
(4) Use twisted pair cables of the same IEC1158-2 technology to complete remote power supply and data transmission.
(5) In areas with potential explosion hazards, explosion-proof “intrinsic safety” or “non-intrinsic safety” types may be used.
1. PROFIBUS-PA transmission protocol
PROFIBUS-PA uses the basic functions of PROFIBUS-DP to transmit measured values and status. It also uses extended PROFIBUS-DP functions to configure field device parameters and perform device operation. The first layer of PROFIBUS-PA adopts IEC 1158-2 technology, and the transition between the second and first layers is specified in Part 4 of the DIN 19245 series standards.
2. PROFIBUS-PA Equipment Specifications
The PROFIBUS-PA specification ensures the interchangeability and interoperability of field devices manufactured by different companies, and it is an integral part of PROFIBUS-PA. The task of the PA specification is to select the actual communication functions required by various types of field devices and to provide all the necessary specifications for these device functions and behaviors.
Currently, PA industry standards have specified requirements for all common measuring transmitters and other optional equipment types, such as:
(1) Transmitters for measuring pressure, level, temperature and flow rate.
(2) Digital input and output
(3) Analog Input and Output
(4) Valves
(5) Positioner
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