BOILER_SEQ
Boiler plant staging against an outdoor-air hot-water reset, with anti-short-cycle protection in both directions.
When to use it
Use BOILER_SEQ when two or more boilers serve one hot-water plant and the supply setpoint should fall as the outdoor air warms, rather than making 82 °C water in April.
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 |
|---|---|---|
| ENABLE | BOOL | — |
| HEAT_REQ | BOOL | — |
| LOAD | REAL | % |
| LOAD_OK | BOOL | — |
| HW_SUP | REAL | °C |
| HW_OK | BOOL | — |
| HW_SP | REAL | °C |
| OA_TEMP | REAL | °C |
| OA_OK | BOOL | — |
| N_BOILERS | USINT | — |
| RESET_EN | BOOL | — |
| OA_LOW | REAL | °C |
| OA_HIGH | REAL | °C |
| SP_MAX | REAL | °C |
| SP_MIN | REAL | °C |
| DB_K | REAL | K |
| UP_PCT | REAL | % |
| DN_PCT | REAL | % |
| UP_DLY | TIME | — |
| DN_DLY | TIME | — |
| MIN_STAGE_TIME | TIME | — |
| FTM_TMO | TIME | — |
| ACK | BOOL | — |
Outputs
| Port | Type | Unit |
|---|---|---|
| STAGE | USINT | — |
| BOILERS_ON | USINT | — |
| HW_RESET_SP | REAL | °C |
| VALID | BOOL | — |
| ALM_FAIL_TO_MAINTAIN | BOOL | — |
| ALM_SENSOR | BOOL | — |
| ALM_CFG_ERR | BOOL | — |
IEC 61499 event interface
EI INIT, REQ·EO INITO, CNF
Validation evidence
- Tests
- 10
- Simulated scans
- 878
- 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
- Conforms to IEC 61499
Download BOILER_SEQ — 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, the IEC 61499 function block type (.fbt) and the datasheet.
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