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Analog/Pulsed Control Valve (P_ValveC)
Do not use this instruction in these situations:
• You are using a single analog output control valve with a PID loop (the
P_PIDE Add-On Instruction or the PIDE built-in instruction). The
CVEU signal can be used directly to drive the valve or you can use the
P_AOut (Analog Output) Add-On Instruction.
• You are using a two-state valve, such as a motor-operated or
solenoid-operated valve that is driven only fully open or fully closed and
not used to control flow or pressure. Use the appropriate two-state valve
instruction instead:
• P_ValveMO for motor operated valve (also for a dual solenoid
operated valve)
• P_ValveSO for a single solenoid operated valve
Functional Description
The P_ValveC Instruction provides the following capabilities:
• Program and operator entry of the target valve position (percentage of
the valve opening).
• Ramping of the valve position to the entered target at a specified rate of
change (percent per second).
• Scaling of the Position Feedback from the valve from raw (I/O card or
network value) units to percent open.
• Monitoring of Interlock conditions. When an Interlock condition is not
OK, the valve can be configured to hold its current position or shed to a
configured Interlock position.
• Monitoring for I/O communication faults. When an I/O communication
fault occurs, this instruction can be configured to alarm only, or to shed,
either to hold the current position or go to the configured Interlock
position.
• Provides alarms for Interlock trip, I/O fault, or an actuator-declared fault.
• Provides full-open and full-closed status based on user-specified ranges for
analog position feedback, or based on optional valve travel limit switches.
• Provides an ‘available’ status when the control valve instruction is in
Program mode and the valve is capable of being controlled.
The diagram shows the functional characteristics of the P_ValveC
Add-On Instruction.
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Rockwell Automation Publication SYSLIB-RM034C-EN-P - August 2014