【Daily Question 20090322】Please share your insights on DCS, PLC, as well as ESD and FCS
Thread Content
Please share your insights on DCS, PLC, ESD, and FCS – you may make comparisons or discuss each topic separately; feel free to express your opinions freely, but the topics must be technical in nature. You can refer to previous posts, but the content should not be repeated. If you are new to the field of process control, you can talk about your own experiences, the products you have come across, as well as any issues or doubts you have (those who are already familiar with this area need not participate). Comments that include practical application experience will be particularly valued. Since it seems that some people here are not clear on some basic concepts, I’ve created this thread for discussion. I hope everyone will organize their thoughts and speak freely, actively participating in the discussion, and those who offer valuable insights will be highly rewarded. This post was last edited by wopale3 on 2009-3-22 19:38.]
PLC evolved from logic control in the process industry, while DCS developed from process control instruments. The former is mainly used for digital control, and the latter for analog control; yet these two technologies now complement each other by leveraging their respective strengths
PLCs are suitable for sequential control and digital interlocking, while DCSs are suited for analog signal processing. Nowadays, there is not much difference between large-scale PLCs and DCSs. The LSYS DCS is also known as FCS; I have not used ESD yet. Pay attention to the explanations from HAIYOU downstairs!
PLC evolved from logic control in the process industry, while DCS developed from process control instruments. The former is mainly used for digital control, and the latter for analog control; yet these two technologies now complement each other by leveraging their respective strengths
The number of analog points that can be processed by a PLC cannot be too large; generally, it should not exceed 1000 points (I’m not entirely sure about this, please correct me if I’m wrong). DCS has a much stronger capability for processing analog signals, with generally no limitations. Therefore, when choosing between PLC or DCS control, note that it depends on the number of analog signals. For small control systems, such as those in sewage treatment plants, PLCs are generally chosen due to their good cost-performance ratio and ease of use in control. For large industrial control systems, such as those in chemical plants, DCS should be chosen, as it offers high processing capacity and stable performance. This post was last edited by chinahbzq on 2009-3-22 18:00]
The DCS systems used in our company’s two sets of equipment are the Yokogawa CS3000 and Honeywell TPS, respectively; for ESD applications, Honeywell’s system is used. Both of them offer good stability. However, personally, I recommend Yokogawa’s DCS as its configuration is simpler and more intuitive.
It mainly comes down to digital and analog control issues. PLCs are used for sequential control and are inexpensive, while DCS systems rely on analog control; their prices are well known: lol