PressureControl.PID

This core function implements an extended PID controller functionality. The pressure value read by the Supervisor is used as the controlled variable. The velocity of the axis is controlled as the manipulated variable. Accordingly, this control structure can be used for a range of tasks:

Holding pressure control in injection molding machines
Back pressure control in injection molding machines
Melt pressure control for extruders
Others

Properties

Name	Type	Access	Description
InitState	BOOL	Get, Set	The core function is not completely and successfully initialized.
FB_PressureControl_PID
Actual	BOOL	Get	Current actual pressure value.
AllowSwitchOver	BOOL	Get, Set	Allows switching from another active Corefunction to pressure control. Notice Currently, only `Ptp` is supported for switching.
Limiting	LREAL	Get, Set	Setpoint for the limitation (e.g., torque, pressure) during pressure control.
Parameters	I_PressureControlParams_PID	Get, Set	Parameter set that is used for control. The parameter sets can be switched by assignment. If a 0 is assigned, the internal parameter set is used.
PressureLookUp	I_PressureLookUp	Get, Set	Print setpoint table for sequential processing of print setpoints. Notice Preliminary implementation
Target	LREAL	Get, Set	Command variable (setpoint) of the controller.
IsEnabled¹	BOOL	Get	A TRUE signals the active state of the pressure switchover. Alternatively: `.AllowSwitchOver`
FB_CorefunctionFeedback
AbortedState	BOOL	Get, Set	Signals the abort of a command by another Corefunction.
BusyState	BOOL	Get, Set	Signals the active execution of a command.
DoneState	BOOL	Get, Set	Signals the successful execution of a command.
IdleState	BOOL	Get, Set	The Corefunction is ready for operation and commandable.
IsCommanded	BOOL	Get	Signals the pending of a command.
FB_Corefunction
FailedState	BOOL	Get, Set	If IsActivated is TRUE at the same time: Signals the failure of an accepted command. If IsActivated is FALSE at the same time: Signals the rejection of a command.
HasFeedback	BOOL	Get	The core function has responded to a pending command.
IsActivated	BOOL	Get	The core function has an accepted command pending.
IsLocalCmd	BOOL	Get	Signals that the axis is assigned with a command of this core function.
ReadyState	BOOL	Get, Set	The Corefunction is ready for operation, but is not commandable at this time. Possible reasons are: - The axis is not enabled. - Another Corefunction is active. - The Corefunction does not support any commands.

Methods

Name	Description
Activate()	Activate / deactivate the controller.
SwitchOver()	Activate the controller by switching another command.
EnableSwitchOver()¹	Enable for automatic activation by a PressureHandler. Alternatively: `AllowSwitchOver`
GetActual()¹	The actual value of the controller is determined. Alternatively: `Actual`
GetParams()¹	An interface to the connected parameter set is determined. Alternatively: `Parameters`
SetParams()¹	A parameter set is connected to the controller. Alternatively: `Parameters`
Setpoint()¹	Set the command variable (setpoint) of the controller. Alternatively: `Target`

¹Obsolete

Interfaces

Type	Description
I_Corefunction	Standard interface on FB_Corefunction.
I_PressureControl	Standard interfaces on FB_PressureControl_PID.
I_CorefunctionFeedback	Standard interface on FB_CorefunctionFeedback.

Example:

// Requires connected pressure input, e.g. via PressureControl.Supervisor.Sensor
// Start pressure control on application start signal 
IF bStart THEN
    
    // Assign pressure setpoint
    iAxisBase.PressureControl.PID.Target := 20.0;
    
    // parameterize once before activation and activate
    IF iAxisBase.PressureControl.PID.IdleState THEN
            
        iAxisBase.PressureControl.PID.Limiting := 80.0;
        iAxisBase.PressureControl.PID.Parameters.Kp := 0.5;
        iAxisBase.PressureControl.PID.Parameters.EnableI := TRUE;
        iAxisBase.PressureControl.PID.Parameters.Tn := 1.0;

        iAxisBase.PressureControl.PID.Activate(TRUE);
        
    // wait until function is terminated
    ELSIF bStop THEN
        
        bStart := FALSE;
        iAxisBase.PressureControl.PID.Activate(FALSE);    
    
    END_IF        
END_IF

Requirements

Development Environment	Target platform	PLC libraries to include
TwinCAT v3.1.4024.66	PC or CX (x64, x86)	Tc3_PlasticFunctions (>= v12.10.0.0)

Further Information