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SOV_SA (Single Acting Solenoid Valve) Logic Block Documentation

Overview

The SOV_SA logic block is used to control single-acting solenoid valves with spring return mechanisms, typically for fail-safe operations. It supports both automatic and manual control, checks for permissions and interlocks, monitors feedback status, and detects faults such as feedback timeouts. The block interfaces directly with HMI faceplates across Operator, Basic, Advanced, and Diagnostic levels.

Logic Block Illustration

../../Images/Programing_Manual/Logic_Manual/SOV_SA/SOV_SA_0.png

In above picture, we are showing inputs and output of SOV-DA block.

  • A visual representation showing how the SOV-SA block connects with inputs, outputs, and HMI indicators.

../../Images/Programing_Manual/Logic_Manual/SOV_SA/SOV_SA_1.png

In the above picture, we are showing that how to use the SOV-DA block

Pins Information

Signal Name Type Description
CMD_OPEN BOOL Manual open command from faceplate
CMD_CLOSE BOOL Manual close command from faceplate
MODE BOOL 0 = Auto mode, 1 = Manual mode
AUTO_CMD BOOL Auto mode command input (TRUE = Open)
PERM_OPEN BOOL Permission to open valve
PERM_CLOSE BOOL Permission to close valve
INTERLOCK_OK BOOL TRUE = Interlock condition satisfied
ZSO_FB BOOL Valve fully open feedback
ZSC_FB BOOL Valve fully closed feedback
ZS_TIMEOUT_SEC TIME Timeout to wait for feedback after command
RESET BOOL Clears faults when TRUE
TAG_NAME STRING Unique name for this valve block
DESC STRING Block description shown on faceplate
CMD_OUT BOOL Output to solenoid coil
VALVE_OPEN BOOL Valve is confirmed open
VALVE_CLOSE BOOL Valve is confirmed closed
CMD_FAULT BOOL Feedback fault detected (timeout or mismatch)
STATUS BYTE 0 = Closed, 1 = Open, 2 = Fault, 3 = Running
OPEN_COUNT UDINT Total number of successful valve openings
CLOSE_COUNT UDINT Total number of successful valve closings
OPENED_TIME TIME Cumulative time valve has remained open (Hrs)

Operational Behavior

Mode Selection

  • Auto Mode (MODE = 0):
  • Valve is driven using the AUTO_CMD input.

  • Only executed if PERM_OPEN, PERM_CLOSE, and INTERLOCK_OK are TRUE.

  • Manual Mode (MODE = 1):

  • HMI buttons (CMD_OPEN / CMD_CLOSE) are active.
  • Commands are validated using permissions and interlock

Command Evaluation

  • Valve commands are only executed if:
  • The corresponding PERM_OPEN or PERM_CLOSE is active.
  • The INTERLOCK_OK condition is TRUE.

Output Activation

  • CMD_OUT is turned ON when the command conditions are met and the valve is expected to change state.

Status Handling

STATUS Value Meaning
0 Valve is fully closed
1 Valve is fully open
2 Command fault has occurred
3 Valve is in transition (Running)
  • VALVE_OPEN and VALVE_CLOSE indicate real-time valve position.
  • CMD_FAULT flags incorrect or delayed feedback signals.

Fault Detection

Fault Condition Signal Affected
No open feedback (ZSO_FB) after open cmd CMD_FAULT = TRUE
No close feedback (ZSC_FB) after close cmd CMD_FAULT = TRUE
Missing permission or interlock Command is blocked
  • Timeout for feedback is governed by ZS_TIMEOUT_SEC.
  • Faults are latched until the user resets using the RESET pin or faceplate button.

Output Summary

  • CMD_OUT: Direct control output to energize the solenoid.
  • VALVE_OPEN / VALVE_CLOSE: Used for HMI indicators.
  • CMD_FAULT: Signals that expected feedback was not received.
  • STATUS: Encoded status for faceplate state visualization.
  • OPENED_TIME_SEC: Tracks duration when valve is open.
  • OPEN_COUNT / CLOSE_COUNT: Track operation cycles.

Notes for Integration

  • Always link CMD_OUT to the coil actuator output in hardware.
  • Use ZSO_FB and ZSC_FB from physical limit switches or position sensors.
  • HMI faceplate should reflect the following:
  • Mode selector (Auto/Manual)
  • Command buttons (OPEN/CLOSE)
  • Fault reset button
  • Feedback indicators (Open/Closed)
  • Alarm banner if CMD_FAULT is active
  • Use TAG_NAME and DESC for diagnostics and navigation in SCADA.

Best Practices

  • Ensure all control signals (permissions and interlocks) are validated before actuation.
  • Configure ZS_TIMEOUT_SEC conservatively based on valve response speed.
  • Maintain consistent naming using TAG_NAME for SCADA traceability.
  • Use runtime counters and fault detection for predictive maintenance dashboards.

The SOV-SA block ensures safe, responsive control of spring-return solenoid valves, with built-in feedback validation and HMI integration for intuitive operator control and diagnostics.