Common fieldbuses include: PROFIBUS, EtherCAT, Lightbus, Interbus, CANopen, ControlNet, SERCOS interface, Ethernet, PROFINET, USB, Modbus, RS232/RS485, CC-Link, AS-Interface, LON, EIB, SNMP, QOS, CAN, and MECHATROLINK.
Advantages of fieldbus: Fieldbus brings automatic control devices and systems into the realm of information networks, opening up a wider range of applications; multiple control devices can be connected to a single twisted pair cable, saving installation costs; reducing maintenance expenses; improving system reliability; and providing users with more flexible control over system integration.
Disadvantages of bus systems: Data packet transmission delays, transient errors and data packet loss in network communication, and inconsistencies in the order of transmission and arrival can all undermine the determinism inherent in traditional control systems, making the analysis and synthesis of control systems more complex and negatively impacting the performance of the control system.
Bus essence
Different organizations and individuals may have different definitions of fieldbus, but generally, it is generally accepted to include the following six aspects:
1. Communication Network
Field communication networks for interconnecting field devices or field instruments used for process automation and manufacturing automation.
2. Device Interconnection
Different field devices or field instruments can be interconnected using different transmission media according to actual needs.
3. Interoperability
Users can choose products from different manufacturers or models to form the required control loop according to their own needs, thus freely integrating FCS.
4. Distributed functional blocks
FCS eliminates the input/output units and control stations of DCS, and distributes the functional blocks of DCS control stations to field instruments in a decentralized manner, thereby forming virtual control stations and completely realizing decentralized control.
5. Power supply for communication lines
The communication line power supply method allows field instruments to draw power directly from the communication line. This method provides low-power field instruments for intrinsically safe environments, and is accompanied by safety barriers.
6. Open Internet
Fieldbus is an open interconnection network that can interconnect with networks at the same layer or different layers, and can also enable the sharing of network databases.
