Honeywell Experion PID parameters explained
Honeywell controllers traditionally express proportional action as a proportional band and reset as minutes per repeat. That combination inverts the direction of a change twice over relative to a gain-and-repeats-per-minute system.
On these systems, making a loop more aggressive proportionally means reducing the number, and making integral action faster also means reducing the number. Both are the opposite of what an engineer arriving from a gain-based system would expect, which is exactly why PIDSnap captures the convention once per plant and phrases every instruction accordingly.
Which direction makes the action stronger
On your system a LOWER proportional number means MORE aggressive proportional action. Proportional band is the inverse of gain.
Reset is in minutes/repeat, so a LOWER number means FASTER integral action.
This is the single most consequential thing to get right. Proportional band and gain move in opposite directions, and so do repeats-per-time and time-per-repeat. An engineer who has moved from one system to another and carried the old habit across will make loops worse while believing they are improving them.
- Proportional term: proportional band
- Reset units: minutes/repeat
- Rate units: minutes
- Algorithm form: ideal noninteracting
Why the algorithm form matters
The algorithm form matters because the same three numbers behave differently in each. In the series (interacting) form the derivative term multiplies the proportional-plus-integral term, so changing rate also changes the effective gain and reset. In the ideal (non-interacting) form the three terms are independent of each other but all scaled by gain. In the parallel (independent) form even that scaling is absent — gain does not affect integral or derivative action at all. Moving a tuning set between systems without converting for form is one of the commonest ways a loop that worked on one plant fails on another.
Before you change anything
Confirm the units on the actual controller rather than trusting the platform default. Systems get configured in unusual ways, engineering units get changed during a migration, and a controller imported from another site may carry conventions from there.
The fastest check is to make a small deliberate change and watch which way the loop responds. If it gets more aggressive when you expected less, the convention is not what you assumed.
Questions that come up
Does Honeywell always use proportional band?
It is the traditional convention and remains common, but configurations vary — particularly on newer systems and on controllers migrated from other platforms. Read the units off the faceplate rather than assuming.
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Last reviewed 2026-08-01.