SOV_DA (Dual Acting Solenoid Valve) Logic Block Documentation

Overview

The SOV_DA logic block is used to control dual-acting solenoid valves, which require explicit actuation signals for both opening and closing actions. This block supports automatic and manual control modes, validates permissions and interlocks, and monitors feedback signals. It reports faults such as command mismatches and feedback timeout.

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

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

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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_OPEN	BOOL	Auto open command
AUTO_CMD_CLOSE	BOOL	Auto close command
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
CMD_OPEN_OUT	BOOL	Output to open solenoid coil
CMD_CLOSE_OUT	BOOL	Output to close 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)
RESET	BOOL	Clears faults when TRUE
TAG_NAME	STRING	Unique name for this valve block
DESC	STRING	Block description

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Operational Behavior

Mode Selection

• Auto Mode (MODE = 0): Controlled using AUTO_CMD_OPEN or AUTO_CMD_CLOSE.
• Manual Mode (MODE = 1): User controls valve using CMD_OPEN and CMD_CLOSE.

Command Execution

• Valve opens/closes only when:
• Corresponding PERM_OPEN/PERM_CLOSE is TRUE

• INTERLOCK_OK is TRUE

• Outputs:

• CMD_OPEN_OUT is TRUE during valid open command

• CMD_CLOSE_OUT is TRUE during valid close command

• Feedback:

• ZSO_FB confirms valve is open
• ZSC_FB confirms valve is closed

Fault Handling

• CMD_FAULT is TRUE when:
• Feedback mismatch occurs (e.g., open command but ZSO not received)
• Feedback not received within ZS_TIMEOUT_SEC

Safe Status Detail

STATUS Value	Meaning
0	Normal
1	Opened and Closed False
2	Opened True
3	Closed True

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Output Summary

Output	Description
CMD_OPEN_OUT	Energizes solenoid to open valve
CMD_CLOSE_OUT	Energizes solenoid to close valve
VALVE_OPEN	TRUE when ZSO_FB = TRUE
VALVE_CLOSE	TRUE when ZSC_FB = TRUE
CMD_FAULT	TRUE if feedback missing or command conflict
STATUS	Valve condition code (Open/Close/Fault/Running)
OPEN_COUNT	Increments on successful OPEN cycle
CLOSE_COUNT	Increments on successful CLOSE cycle
OPENED_TIME_SEC	Aggregated valve open duration

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Best Practices

• Set ZS_TIMEOUT_SEC carefully to avoid false alarms.
• Always check PERM and INTERLOCK_OK signals before allowing manual command.
• Use fault output CMD_FAULT to trigger alarms or diagnostics.
• Use OPEN_COUNT, CLOSE_COUNT, and OPENED_TIME_SEC for maintenance analysis.
• Maintain unique TAG_NAME for tracking and SCADA linking.

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This logic ensures safe, redundant, and clear actuation and monitoring for dual-acting solenoid valves in process control systems.