Which of the 3 configuration options for the DCS system’s field HMI is the best?
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I would like to discuss with everyone the following three methods of connecting multiple HMI human-machine interfaces at a site in Zone 2 explosion-proof areas to the DCS main control network: 1. Using HMI all-in-one units (that is, integrated PCs on-site, explosion-proof, 24VDC). 2. An on-site HMI display screen is used, with a dedicated PC host placed in the cabinet; the two are connected to each other via communication cables/optical fibers. 3. An on-site HMI display screen is used, with servers (located in the cabinet room) connected in a star topology via redundant switches; if a server fails, it can be replaced by another server in the system. The first two methods are the most commonly used at present, but HMI units in large quantities come at a higher cost. The last method is the one recommended by suppliers today; it offers good cost-performance, yet there are concerns regarding potential issues during use, such as speed and the time required to switch to a backup server in the event of a server failure. Those with experience can share their thoughts on using it~
I won’t go into the first option; as for the second one, should the PC be placed in the cabinet room while the monitor is installed on-site? This third one is more or less the same. Decentralization doesn’t save money, but it is reliable.
Is it really necessary to get these useless things on-site? They’re not cheap at all.
Could experts elaborate on the third method? How is it generally implemented? Also, among the international and domestic explosion-proof screens or all-in-one devices available on the market today, which manufacturers are generally considered to produce high-quality products?
The second type seems to have a 2-3 second delay when the distance is large