HYSTERESIS
Two-threshold on/off switch with independent on- and off-delays and a declared fail state.
When to use it
Use HYSTERESIS when a boolean has to be derived from an analog value — a level switch calling a pump, a pressure switch starting a compressor, a temperature switch enabling a stage — and the analog value will sit near the threshold for long periods.
Interface
The published port signature. This is the whole of what the block exposes to your program — the implementation body is not shown here and ships with the download.
Inputs
| Port | Type | Unit |
|---|---|---|
| IN | REAL | eng. units |
| HI | REAL | eng. units |
| LO | REAL | eng. units |
| ON_DLY | TIME | — |
| OFF_DLY | TIME | — |
| IN_OK | BOOL | — |
| FAIL_Q | BOOL | — |
Outputs
| Port | Type |
|---|---|
| Q | BOOL |
| IN_BAND | BOOL |
| VALID | BOOL |
| ALM_CFG_ERR | BOOL |
Validation evidence
- Tests
- 9
- Simulated scans
- 270
- Simulator
- v0.1.0
Complete IEC 61131-3 implementation with a published test suite that runs on the vplant simulator. The counts above are that suite, executed on this build.
- Conforms to IEC 61131-3
Download HYSTERESIS — free
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