PROFIBUS system overview
The Beckhoff Embedded PCs can be ordered ex works with an optional interface, e.g. PROFIBUS, CANopen or RS232. Some of the optional interfaces can be delivered as master or slave.
The following Embedded PCs can be ordered with an optional interface:
- CX9020
- CX50x0
- CX51x0
- CX20x0
PROFIBUS master (M310)
The optional interface M310 is a PROFIBUS master and enables a segment-like construction of control structures in large plants and machines. Further Beckhoff fieldbus components such as Bus Couplers, Bus Terminal Controllers, drive components, etc. can be used with an Embedded PC for configuring control structures.
Fieldbus masters are used for decentralized collection of process data and signals in large machines and plants. The number of slaves that can be connected to the master is only limited by the respective bus system. Using master and slave connections makes it possible to link several Embedded PCs with each other via the fieldbus level.
The optional interfaces are detected, parameterized and configured in TwinCAT, and the connected I/O components are added. TwinCAT is also used for diagnostics.
PROFIBUS slave (B310)
The optional interface B310 is a PROFIBUS slave and enables an Embedded PC to be used as subordinate decentral controller for configuring complex or modular systems.
The PROFIBUS slave receives external process data from the master and processes them or returns data from its own process periphery to the master after processing.
Like the PROFIBUS master, the optional PROFIBUS slave interface is parameterized and configured in TwinCAT.
Functioning
PROFIBUS is a manufacturer - independent, open fieldbus standard with a wide range of applications in manufacturing and process automation. Manufacturer-independence and openness are guaranteed by the International standards EN 50170 and EN 50254.
Further Information |
|---|
PROFIBUS User Organization (PNO): |
PROFIBUS allows devices from different manufacturers to communicate without the need for specially adapted interfaces. PROFIBUS is suitable both for fast, time-critical applications and for complex communication tasks.
In PROFIBUS DP, central control devices (e.g. Industrial PCs or PLCs) communicate via a fast serial connection with decentralized input and output modules. RS485 is the most frequently used transmission technique, using a screened twisted pair cable. Data is mainly exchanged cyclically, although acyclic services (DP-V1) are available for paramétrisation and diagnosis.
PROFIBUS DP offers short system response times: at a transmission rate of 12 Mbaud, less than 2 ms are required to transmit 512 bits each of input and output data to 32 devices.
All Beckhoff PROFIBUS devices feature a high-performance protocol implementation and are certified by the PROFIBUS user organization (PNO).
PROFIBUS distinguishes the following device types:
Master devices determine the data traffic on the bus. A master may transmit messages without having received an external request when it is in possession of the bus access authorization (token). Masters are also referred to as active devices.
Slave devices are peripheral devices such as input/output devices, valves, drives, measuring transducers and the Beckhoff PROFIBUS slaves from the BK3xx0, BC3xx0, IPxxxx-B310, IL230x-B310 and IL230x-C310 series. They do not receive any bus access authorization, so that they are only allowed to acknowledge messages that have been received, or to send messages in response to a request from master. Slaves are referred to as passive devices. They only require a small proportion of the bus protocol, which means that they can be implemented with little effort.
PROFIBUS-DP
PROFIBUS DP is designed for efficient data exchange at the field level. The central automation devices such as PLC/PCs or process control systems communicate here over a fast serial link with decentralized field devices such as I/O, drives, valves, etc. Data is primarily exchanged with these distributed devices cyclically. The communication functions required for this are specified by the basic DP functions conforms to EN 50170.
Beyond these basic functions, PROFIBUS DP offers advanced acyclic communication services for paramétrisation and operation, for example, which are supported by Beckhoff PROFIBUS slaves of the IPxxxx-B310, IL230x-B310 and IL230x-C310 series. A central controller (master) cyclically reads the input information from the slaves and cyclically writes the output information to the slaves. The bus cycle time here should be shorter than the central automation system's program cycle time, which lies around 10 ms in many applications.