LAG_1ST
First-order low-pass filter with a scan-rate-independent time constant and initialisation onto the live signal.
When to use it
Use LAG_1ST when a measurement is noisy enough to disturb a controller or an alarm — a flow on a reciprocating pump, a differential pressure across a filter, a current measurement, a pressure downstream of a valve — and the noise is faster than the process.
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 |
| TC | TIME | — |
| CYCLE | TIME | — |
| IN_OK | BOOL | — |
| RESET | BOOL | — |
Outputs
| Port | Type | Unit |
|---|---|---|
| OUT | REAL | eng. units |
| VALID | BOOL | — |
Validation evidence
- Tests
- 7
- Simulated scans
- 355
- 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 LAG_1ST — free
Create a free Ri Tech account to download the block. You get the Structured Text body, the Rockwell Add-On Instruction (.L5X), the Schneider Control Expert DFB (.XDB), PLCopen XML and the datasheet.
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Source is never published on this page. The implementation is released to a signed-in Ri Tech account — free of charge, but never anonymously.