DEW_POINT_CALC
Magnus dew point with guarded inputs, air-side margin and a confirmed, latched condensation-risk alarm for a monitored cold surface.
When to use it
Use DEW_POINT_CALC when dew point is needed from a temperature/humidity pair — for the ASHRAE envelope, for a humidifier or dehumidifier loop, or to hold a chilled-water or in-row coil surface above the point at which it drips onto energised equipment.
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 | — |
| T | REAL | °C |
| RH | REAL | % |
| T_RANGE_LO_C | REAL | °C |
| T_RANGE_HI_C | REAL | °C |
| RH_RANGE_LO | REAL | % |
| RH_RANGE_HI | REAL | % |
| T_OK | BOOL | — |
| RH_OK | BOOL | — |
| SURF_T | REAL | °C |
| SURF_OK | BOOL | — |
| MARGIN_MIN_K | REAL | K |
| CONFIRM_T | TIME | — |
| ACK | BOOL | — |
Outputs
| Port | Type | Unit |
|---|---|---|
| DEWPOINT | REAL | °C |
| MARGIN_K | REAL | K |
| SURF_MARGIN_K | REAL | K |
| COND_RISK | BOOL | — |
| ALM_COND_RISK | BOOL | — |
| ALM_RH_CLAMPED | BOOL | — |
| ALM_SENSOR_FAULT | BOOL | — |
| ALM_SENSOR_RANGE | BOOL | — |
| VALID | BOOL | — |
IEC 61499 event interface
EI INIT, REQ·EO INITO, CNF
Validation evidence
- Tests
- 10
- Simulated scans
- 132
- 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 DEW_POINT_CALC — 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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Source is never published on this page. The implementation is released to a signed-in Ri Tech account — free of charge, but never anonymously.