Reset units converter
Reset is expressed four different ways across the systems in common use, and two of them run in the opposite direction to the other two. Getting the conversion backwards does not produce a slightly wrong loop; it produces a loop tuned the opposite way to what was intended.
This converter handles all four conventions in both directions.
| Repeats/minute | Minutes/repeat | Seconds/repeat | Repeats/second |
|---|---|---|---|
| 0.5 | 2 | 120 | 0.008333 |
| 1 | 1 | 60 | 0.01667 |
| 2 | 0.5 | 30 | 0.03333 |
| 4 | 0.25 | 15 | 0.06667 |
| 10 | 0.1 | 6 | 0.1667 |
| 30 | 0.03333 | 2 | 0.5 |
Why the direction flips
Repeats per minute counts how often the integral action repeats. More repeats means faster integral action, so a bigger number is more aggressive.
Minutes per repeat measures the time between repeats. More time means slower integral action, so a bigger number is less aggressive.
The two are reciprocals: four repeats per minute is a quarter of a minute per repeat. Because it is a reciprocal rather than a scaling, the error from getting it backwards is not a constant factor — it grows as the values move away from one.
Which convention does my system use?
Common defaults, all of which should be confirmed against the actual controller rather than assumed:
- DeltaV — minutes per repeat (sometimes seconds; check the block).
- Ovation — repeats per minute.
- SIMATIC PCS 7 — integral time in seconds.
- Rockwell PIDE — minutes per repeat in dependent form.
- Yokogawa Centum — seconds per repeat.
- Honeywell — minutes per repeat.
Questions that come up
What does a reset of zero mean?
It depends on the units, and the two meanings are opposite. Zero repeats per minute means integral action is switched off. Zero minutes per repeat would mean infinitely fast integral action, which is why controllers using time-per-repeat units generally treat zero as 'off' by convention rather than literally.
Related
Last reviewed 2026-08-01.