A newcomer asks: how is the number of IO points in a control system determined?
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A newcomer asks: how is the number of IO points in a control system determined? Are there any relevant materials available for learning* it? https://bbs.hcbbs.com/forum.php?mod=image&aid=1807264&size=300x300&key=fdc14aff230a958c&nocache=yes&type=fixnone
It depends on the number of devices you connect. One transmitter represents one AI point (for things like temperature, pressure, flow rate, level, etc.). Control valves and frequency converters correspond to 1AO points and 1AI points respectively. Some devices also provide DI feedback; the number of DI signals depends on the number of functions integrated into the system. Pumps require at least 1 DI and 2 DO signals. Various switch-type instruments generate DI signals, with the number of DI signals corresponding to the number of switches. The start/stop control of pumps and the opening/closing control of switch valves are handled by DO points. These are the commonly used types I mentioned: lol
Is this a summary of experience? Are there still relevant materials available for reference?
:L What’s this? . Consider it experience – when I set up the factory, I handled everything myself. After working for a while, you learn which devices correspond to which terminals; these are the basic terminals
A signal that is connected to the system via hard wiring is called a hard point, including inputs and outputs. However, the soft points of a control system include, in addition to the hard points, the intermediate values used to implement the control process algorithms, as these take up memory space in the controller. A controller cannot be assigned too many soft points. You can get the “reference” you need by simply buying any book related to process control systems.
Calculate the number of input and output points based on the number of devices selected per design, and then leave some extra for backup.
By the way, after designing it, you should leave around 15-25% of slots reserved; you can’t count everything that’s there. When doing the calculations, use the number of slots specified in the design
Some DCS software allows for the counting of AI/AO/DI/DO points; the control configuration diagrams can also be used for this purpose, as well as the DCS hardware wiring cabinets. It is also possible to determine what type of cards are used, how many channels they have, and how many channels are connected to each card；
Check the PID and complete equipment documents