Cascade controller set-point units
Cascade controller set-point units
(OP)
When a controller accepts a remote set-point in cascade mode from another (primary) controller does the output of the primary controller have to be scaled into the engineering units of the secondary measured value (MV)?
RE: Cascade controller set-point units
xnuke
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RE: Cascade controller set-point units
But, I've worked on some DCS Systems that don't allow changing the Output Engineering Units of the Primary Controller - they were always 0 - 100% and could not be changed to match the engineering units of the secondary controller (like degC). It's very frustrating.....
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RE: Cascade controller set-point units
RE: Cascade controller set-point units
RE: Cascade controller set-point units
0-100% of the Master controller output represents the full range of the Secondary controller PV...in your example 0 - 50 lpm.
Keep in mind that typically the Setpoint range of the secondary controller matches the PV Range...so your SP Range would also be 0 - 50 lpm.
If you limit your setpoint maximum to, for example 40 lpm, the 100% output still represents the 50 lpm but the secondary controller won't go above 40.
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This is normally the space where people post something insightful.
RE: Cascade controller set-point units