Industrielle styresystemer - Wiki
The function block "EbbFlow" controls ebb and flow for an independent plant tank. The function block is made to be controlled from a SCADA system. From SCADA system you have many options. For example, override Ebb Valve and Flow Valve. You can set times to control duration of both Ebb sequence and Flow sequence. Also, you can set times for exercise intervals and duration of this. This to ensure longest possible life of the valves. Further, you can manually activate ebb or flow sequence. So if tank is in ebb for 5 more hours, and you want flow now. Then function will immediately start ebb sequence, and continue normal after this.
If flow mode is active then fill valve will be open until level switch is active or flow time is up. In this sequence drain valve will also be closed. In ebb mode, the ebb valve will be open for a given time (this to ensure valve is not open unnecessarily long). When time "TimeEbbValveOn" is up, then drain valve will close and tank will be empty without water. Flow valve will then be closed. Until ebb time is up, after this it goes back to fill mode again.
Function block gives out which status all valves are in, if level switch is on, how much time is left of current mode (ebb or flow) and which mode is active.
Override ventiler
| Override Value | Description |
|---|---|
| 0 | Auto |
| 1 | Manual On |
| 2 | Manual Off |
Valve states,
| Override Alarm Value | Description |
|---|---|
| 0 | Auto Off |
| 1 | Auto On |
| 2 | Manual On |
| 3 | Manual Off |
| 4 | Motion |
With everything explained the Inputs and Outputs are the following,
INPUT
- Start → BOOL
- StartFlow → BOOL
- StartEbb→ BOOL
- TimeFlow → TIME
- TimeEbb→ TIME
- LevelGuardIn → BOOL
- TimeEbbValveOn→ TIME
- OverrideFlowValve → INT
- OverrideEbbValve → INT
- MotionInterval→ TIME
- MotionDuration → TIME
OUTPUT
- StateEbbValve → INT
- StateFlowValve→ INT
- OUT → BOOL
- LevelGuardOut→ BOOL
- OutEbbValve → TIME
- OutFlowValve → TIME
- TimeRemaining→ TIME
- ModeEbb → BOOL
- ModeFlow → BOOL
INTERNAL VARIABLES
- LevelGuard→ LEVELGUARD
- EbbDuration→ TON
- FlowDuration→ TON
- FlowValve → MOTORVALVE
- PULSE_1 → PULSETHREESECONDS
- PULSE_2 → PULSETHREESECONDS
- PULSE_3 → PULSEFOURSECONDS
- EbbValveOpen → TOF
- EbbValve→ MOTORVALVE
- TimerMotionInt1 → TON
- TimerMotionDur1 → TOF
- TimerMotionInt1 → TON
- TimerMotionDur1 → TOF
- HighLowSelect → HIGHLOWSELECT
CODED SOLUTION
Variable Decleration:
CODE:
Overview
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