I would like to ask about the number of points in DCS
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I have a question for everyone: How is the number of points calculated for DCS systems and SIS systems? For example, a locator has inputs and outputs, and an I/O card; is the input/output counted as one point? Should entering I count as one point, and outputting O count as one point as well? I’m an amateur when it comes to systems, and I doubt I’ll be able to pose any questions. I hope the experts here can explain things in detail. Thank you! ! ! Here, I wish everyone that in 2017, they will get whatever they desire – wind when they need it, rain when they need it – and that they will face challenges together to achieve greatness!
If there are inputs and outputs, then it is AI; there is one AO element and a total of 2 analog elements. Typically, the control output AO is implemented as a redundant card, while the valve position feedback AI is a non-redundant card.
Counted by the number of points entering and exiting the DCS
Input and output are counted separately
It is determined by whether there is one point or two points for the valve; if it is single-acting, then 0 means open and 1 means closed, which corresponds to one point
So, does that mean that by counting the number of cables coming in and going out of the DCS, it’s possible to determine the number of points in the DCS?
For example: How many points are there on the DCS for a transmitter that measures tank pressure or a transmitter that measures differential pressure? How many points does a 4-20mA signal transmitted by a valve positioner represent on a DCS? In other words, is a two-core cable considered one point? For the valve position signal of the cut-off valve, should one point be counted for the open position (one cable), one point for the closed position (one cable), or one point for both the open and closed positions (two cables)? Sometimes the system administrators say that this system has 500 points, so just how large is this system exactly? There is no clear concept at all in the brain. Also, the DCS system is bid on based on points; I would appreciate some advice from those who are more experienced in this area.
To be honest, are there two issues with the control valve positioner? I still haven’t seen it. 322 cards are enough to handle one point; does the control valve provide feedback? Only on-off valves have inputs and outputs, and feedback is required in the case of DIDO signals. To calculate the points, please contact the design institute; they will do the calculation for you
Well, the calculation of the points is related to the instruments; the configuration of the DCS is determined based on those points, rather than the points being determined by the DCS. On the instrument panel, for example, a temperature transmitter represents an AI point; whereas if a control valve is equipped with feedback, it constitutes one AI and one AO, while in the absence of feedback, there is only one AO. The cut-off valves correspond to DI and DO; the specific number depends on the configuration of your cut-off valves. And if you count the total, it’s AI, AO, DI, and DO added together. . In summary, the number of points is determined by the instrument, and the DCS configuration is based on that number of points. It can’t be reversed! ! ! !