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Adam Klama, 06/21/2026 02:14 PM

Compare Input

Overview

A Compare Input produces a boolean by comparing a source input against a
value. The result follows the standard convention: true = 1024, false = 0. Use
it to turn a measurement into an on/off condition — for example "oil pressure is
below the warning limit" or "speed is inside the shift window" — that other logic,
outputs or maps can act on.

Prerequisites

You need:

  • A source input to compare — any existing input, referenced by its alias.
  • The value to compare against. This can be a fixed number, or you can point
    the source/value at a Constant Value Input if you
    want a tunable threshold.

Add it in the app

  1. Add a new input and choose Compare Input as the type.
  2. Choose the source input.
  3. Give it a clear alias (e.g. Low Oil Pressure).
  4. Set the compare mode, the value, and a deviation for hysteresis.
  5. Enable the filter and set the debounce timings if the result still chatters.

Settings reference

Schema: config/CompareInput.proto.

Setting Meaning Unit Range / values Notes
Source input The input being compared — an existing input (by alias) The value tested against Value.
Compare mode How the comparison is made — Equal, LessThan, GreaterThan, WindowCompare See below. Result is 1024 (true) or 0 (false).
Value The value to compare against source's unit int32 The threshold/reference point for the comparison.
Deviation Hysteresis band around the threshold source's unit int32 Adds hysteresis so the result doesn't chatter as the source crosses Value — it switches at one edge of the band and clears at the other. (In WindowCompare it also sets the half-width of the in-range window.)
Enable filter Turns on debounce of the boolean result — on / off Recommended when the source hovers near the threshold. The three timings below apply when on.
Delay Time the new result must be stable before it is accepted ms sint32 Suppresses brief flips around the threshold.
Hold Minimum time a result is held once accepted ms sint32 Stops rapid re-triggering.
Interspace Minimum gap between result changes ms sint32 Ignores changes that arrive closer together than this.

Compare modes: Equal, LessThan and GreaterThan test the source against
Value. WindowCompare is true while the source sits within Value ± Deviation — handy for "in range" checks.

Hysteresis vs debounce: Deviation is the first defence against chatter —
it gives the threshold a dead-band so the result doesn't flip rapidly as the source
hovers around Value. The Delay / Hold / Interspace debounce timings are a
time-based backup if the result still chatters.

Common settings

Compare Input also uses the shared setting — alias. See Common IO Settings.

Example — low oil-pressure warning

  1. Type Compare Input, alias Low Oil Pressure.
  2. Source input = your Oil Pressure input.
  3. Compare mode LessThan, Value 100 (your low-pressure limit),
    Deviation 10 so it trips below 90 and clears above 110 (hysteresis).
  4. Optionally Enable filter, Delay 200, Hold 500 so a momentary dip
    does not trip the warning.

The input now reads 1024 (true) whenever oil pressure is below the limit, 0
otherwise.

Troubleshooting

  • Result chatters on/off: increase Deviation for more hysteresis; if it
    still flips, enable the filter and raise Delay / Interspace.
  • Always true or always false: check the compare mode and that Value
    is in the same units as the source input.
  • Window Compare never true: Deviation is too small, or Value is not
    the centre of the band you expect.

Related

Updated by Adam Klama 1 day ago · 3 revisions