For the valves in the SIS interlock, should the feedback signal go to the DCS or to the SIS?
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For valves interlocked with the SIS, it goes without saying that solenoid valves must be connected to the SIS. But what about the feedback signals? Must they also be fed into the SIS system, or can they also be directed to the DCS?
Feedback can be fed into the DCS. The normal DCS interface should also be able to monitor the status of SIS valves; it’s more convenient to have this information directly in the DCS
It is necessary to access the SIS system; many chains use feedback from valves to determine the status, and it is also possible to send a set of signals to the DCS – by selecting the appropriate isolator this can be achieved
It is possible to go into SIS first and then map the signals to DCS. In this way, both the input and output of the interlock are within the SIS; meanwhile, the DCS can also obtain information regarding the valve status.
If the feedback signal is used in the SIS interlock, it is necessary to enter the SIS system; the signal is then displayed in the DCS through a signal distributor or communication means. If it is not used in the SIS interlock, there is no need to enter the SIS system – one can go directly to the DCS system
Enter SIS to facilitate diagnosis of SIS function blocks
The feedback signal must be routed to the DCS; this allows the DCS to monitor the status of SIS valves at any time. This is a requirement stipulated in all expert inspections
Perhaps the SIS system I’m using isn’t powerful enough; therefore, feedback is required to confirm the opening/closing of the valves