Table of Contents

AxisListenerSequence

Namespace
ZEquipment
Extends
Inherited Properties
Inherited Methods
Implements
FUNCTION_BLOCK ABSTRACT AxisListenerSequence EXTENDS ZAux.Sequence IMPLEMENTS ZCore.ISequence, ZCore.IHaltable, ZCore.ICancellationToken, ZCore.IHaltToken, ZCore.IStartToken, ZCore.IError, ZCore.IObject, ZCore.IRecoverable (
 [input] Axis : IAxisBase,
 [input] ListenerState : ZAux.StateMachineListenerState,
 [input] ListenerType : AxisListenerType,
 [output] State : ObjectState,
 [output] Diagnostics : DiagnosticMessage)

This function block is the base class for any listener for axis actions. The function block is linked to an axis via an interface, which is passed during construction of the listener. The axis calls all listeners, linked to it, before and after any action and also in case of error. The ListenerState variable give the context to when (before, after, during, ...) the sequence is called, ListenerType variables gives the context why (for which action) the sequence is being called. The Axis variable points to the axis, which invoked the listener.

  • A listener sequence can be used to perform an arbitrary action and/or abort the movement of the actuator. To implement an action you can use Steps or any other objects to control the sequential flow. After the action is performed SetBusy(FALSE) has to be called such that the axis can proceed with its sequence. The only exception here is the the action state PreError. If an axis has an error the listener sequences are only called once and then stopped immediatelly to continue with the actual fault reaction of the axis.
  • Sometime it is necessary to prevent an axis from a movement due to various cirumstances (e.g. it would collide with something). For this use case simply call the Abort method (or any of its derivatives), of the sequence to prevent the movement.

To implement a listener, simply extend from this object and implement the body of your function block, as the following example shows.

FUNCTION_BLOCK DummyAxisListenerSequence EXTENDS ZEquipment.AxisListenerSequence
VAR
  _timer : ZAux.Timer;
END_VAR

IF OnStart(0)
THEN
  _logger.AtInfo().Append('Enter AxisListener (')
                  .AppendParamString('ListenerType:', ListenerTypeDecoded(THIS^.ListenerType))
                  .Append('; ')
                  .AppendParamString('ListenerState:', ListenerStateDecoded(THIS^.ListenerState))
                  .LogMessage(')');  
  _timer.WaitAsync(5);
END_IF

CASE THIS^.ListenerType
OF
  ZEquipment.AxisListenerType.Enable:
    CASE THIS^.ListenerState
    OF
      ZAux.StateMachineListenerState.PreActive:
          IF _timer.Done
          THEN
            _logger.Info('Waited 5s');
             SetBusy(FALSE);
					END_IF

      ZAux.StateMachineListenerState.PostActive:
          IF _timer.Done
          THEN
            _logger.Info('Waited 5s');
            SetBusy(FALSE);     
					END_IF     
    ELSE 
      SetBusy(FALSE);
    END_CASE
 
ELSE
  SetBusy(FALSE);
END_CASE

IF NOT Busy
THEN
  _logger.AtInfo().Append('Exit AxisListener (')
                  .AppendParamString('ListenerType:', ListenerTypeDecoded(THIS^.ListenerType))
                  .Append('; ')                     
                  .AppendParamString('ListenerState:', ListenerStateDecoded(THIS^.ListenerState))
                  .LogMessage(')');  
END_IF
Warning

Make sure the listener sequences eventually calls SetBusy(FALSE), otherwise axis actions may be blocked forever. The only exception here is for ListenerState=PreError, because the statemachine will only call the listener sequence once (for safety)

The minimum implementation of the sequences's body therefore is SetBusy(FALSE);!

Inputs

Axis IAxisBase

Axis calling the sequence

ListenerState StateMachineListenerState

Reason when the axis is calling the sequence

ListenerType AxisListenerType

Reason why the axis is calling the sequence

Constructor

FB_init 

METHOD FB_init (
 [input] bInitRetains : BOOL,
 [input] bInCopyCode : BOOL,
 [input] axis : REFERENCE TO Axis) : BOOL

Inputs

bInitRetains BOOL

if TRUE, the retain variables are initialized (warm start / cold start)

bInCopyCode BOOL

if TRUE, the instance afterwards gets moved into the copy code (online change)

axis REFERENCE TO Axis

Returns

BOOL

Methods

ListenerStateDecoded 

METHOD ListenerStateDecoded (
 [input] listenerState : ZAux.StateMachineListenerState) : STRING

Inputs

listenerState StateMachineListenerState

Returns

STRING

ListenerTypeDecoded 

METHOD ListenerTypeDecoded (
 [input] listenerType : AxisListenerType) : STRING

Inputs

listenerType AxisListenerType

Returns

STRING