DCW_COND_BLOWDOWN
Conductivity-controlled cooling-tower bleed with biocide lockout, two-way bleed supervision and blowdown totalising.
When to use it
Use DCW_COND_BLOWDOWN when a cooling tower or evaporative condenser bleeds to drain on basin conductivity to hold cycles of concentration, and the bleed has to be held shut during biocide dosing and supervised both for a bleed that achieves nothing and for a valve that keeps passing after the command has dropped.
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 | — |
| COND_US | REAL | µS/cm |
| COND_OK | BOOL | — |
| SP_US | REAL | µS/cm |
| DB_US | REAL | µS/cm |
| BLEED_LOCKOUT | BOOL | — |
| BD_FLOW | REAL | m3/h |
| MIN_BD_FLOW | REAL | m3/h |
| FLOW_TMO | TIME | — |
| MAX_BD_TIME | TIME | — |
| COND_HI_US | REAL | µS/cm |
| COND_LO_US | REAL | µS/cm |
| ACK | BOOL | — |
Outputs
| Port | Type | Unit |
|---|---|---|
| BLEED_CMD | BOOL | — |
| BLEEDING | BOOL | — |
| BLEED_HELD | BOOL | — |
| BD_TOTAL_LIFE_M3 | REAL | m3 |
| BD_HOURS_LIFE | REAL | h |
| BD_MEAN_M3H | REAL | m3/h |
| BD_MEAN_VALID | BOOL | — |
| ALM_COND_HI | BOOL | — |
| ALM_COND_LO | BOOL | — |
| ALM_BD_TMO | BOOL | — |
| ALM_NO_BD_FLOW | BOOL | — |
| ALM_BD_LEAK_BY | BOOL | — |
| ALM_COND_FAULT | BOOL | — |
| ALM_CFG_ERR | BOOL | — |
IEC 61499 event interface
EI INIT, REQ·EO INITO, CNF
Supervised control write
DCW_COND_BLOWDOWN commands a real actuator. It is written to sit underneath your own interlock, permissive and protection logic — not to replace it. Commission it as you would any control block you wrote yourself.
Validation evidence
- Tests
- 13
- Simulated scans
- 689
- 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 DCW_COND_BLOWDOWN — 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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