Can DCS implement this control scheme?
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Can DCS implement this control scheme? For example, an AI input minus a set value yields a deviation value; the range of this deviation value is assumed to be -30 to 30. This deviation value is fed into the PID module, whose set value is 0, with an output range of -5 to 5. Can it be done?
The PID output ranges from 0 to 100%; how can I get it to range from -5 to 5?
It depends on which DCS you use; the logical modules vary from one DCS to another, but it should be possible to achieve what the original poster mentioned
It depends on which DCS you use; the logical modules vary from one DCS to another, but it should be possible to achieve what the original poster mentioned
Of course, a PID can output values ranging from -5 to 5. For example, if a PID is the main PID in a cascade control system, then its output range will be the same as the range of the variable downstream. If your downstream value is between -5 and 5, his output range will also be between -5 and 5.
A 0–100% linear conversion to -5~5 – isn’t that very simple?
What was mentioned above is a simple constant-value control system, whose control model is applicable to single-loop constant-value regulation systems. In a control system, the deviation is the set value minus the measured value. In DCS, the unit of process values can be engineering units or percentages. Processing of this type is the most basic function of DCS.
It’s possible, but it’s not conducive to recording trend curves.