1. DCS control system:
Communication is crucial to a DCS control system; the data highway is the spine of the DCS, providing a communication network between all components. Therefore, the design of the data highway itself determines the overall flexibility and security. The medium for the data highway can be a twisted pair of wires, coaxial cable, or fiber optic cable. By examining the design parameters of the data highway, we can understand the relative advantages and weaknesses of a specific DCS control system. To ensure system security, complex communication protocols and error detection technologies are used. A communication protocol is a set of rules to ensure that transmitted data is received and understood in the same way as the sent data. Currently, DCS control systems generally use two types of communication methods: synchronous and asynchronous. Synchronous communication relies on a clock to regulate data transmission and reception, while asynchronous networks use a clockless reporting system.
2. FCS Control System:
The core of the FCS control system is the bus protocol, i.e., the bus standard. Once the bus protocol is determined, the related key technologies and equipment are also determined. In terms of the basic principle of the bus protocol, all types of buses are the same, based on solving bidirectional serial digital communication transmission. However, due to various reasons, there are significant differences in the bus protocols of various buses. In order to meet the interoperability requirements of the fieldbus and make it a truly open system, the original IEC international standard, in the user layer of the fieldbus communication protocol simulation, clearly stipulates that the user layer has a device description function. To achieve interoperability, each fieldbus device is described by a device description (DD). The DD can be considered as a driver of the device, which includes all the necessary parameter descriptions and the operating steps required by the master station. Since the DD includes all the information needed to describe device communication and is independent of the master station, it enables true interoperability of field devices. Currently, many fieldbuses have been developed, such as Interbus, Bitbus, DeviceNet, MODbus, Arcnet, P-Net, FIP, ISP, etc., among which the five most influential are FF, Profitbus, HART, CAN, and LonWorks.
Performance comparison table of FF, Profitbus, HART, CAN and LonWorks:
