There is delay or error in the display of field instrument signals in DCS
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The on-site operation station has been removed, and the signals from the on-site cabinet room are transmitted to the operation station in the central control room via a bus. The cable length is approximately fifty meters; however, after this connection, there is a delay in the feedback signals from the on-site valves, and errors occur in the signals from other instruments. What could be the reason for this? I would appreciate any advice you can provide. Thank you.
After the modification was completed, did you do debugging again?
Communication itself involves latency; one reason why it cannot be used for interlocking is precisely this latency. Additionally, the operation station can be moved to the central control room, but the controllers cannot; they must remain in the on-site cabinet rooms. The true meaning of DCS is decentralized control. If all the controllers are moved, then not only will there be delays as seen from the central control room, but there will also be delays in the on-site adjustment and interlock control actions……
Hello, thank you for your advice. How should I debug it? Which parameters should be adjusted?
Thank you. The controller hasn’t been moved; the cabinet is still on site. Only an optoelectronic converter was added, with twisted pair cables leading to the central control room, and that’s when delays and errors occurred.
What brand of DCS? I recently carried out a relocation of an operation station, using fiber optics along with transceivers, and now the signal is very stable. Question 1: What is transmitted to the central control room via the bus? Question 2:
Question 2: Is it just a matter of moving the host computer, that is, the PC, to the control room? If that’s the case, I suggest you test the optical fibers or replace one of them. We installed 8 optical fibers in total, but we only use two of them. If there are any issues, we can discuss them, or you can send a picture to show how it’s configured and converted on both ends. Theoretically, these devices are needed; a fiber optic terminal box, fiber optic transceivers, switches, and network cables will do as well
No need, I’ve seen control rooms that are hundreds of meters away from the on-site DCS
Well, signal attenuation occurs even when using an Ethernet cable over a distance of 100 meters. Could you tell me about your current transmission equipment and other relevant details?
The upper-level computer was simply moved to the central control room; an optoelectronic converter was added to the on-site cabinet area, and the signals were transmitted to the cabinet room in the central control room via shielded twisted pair cables.
What’s the use of an optoelectronic converter if there are no optical fibers? It shows a lack of understanding