MC_CyclicSwitch

Function block MC_CyclicSwitch
Uses an axis' position to control a switch that triggers a digital output repeatedly. When an axis reaches a certain position, a switch is turned on or off. A switch can be controlled by a forward and backward movement of an axis.
VAR_IN_OUT
V AxisIn AXIS_REF Reference to an axis.
V OutputIn MC_OUTPUT_REF Selects which digital output will be controlled by the corresponding track.
V CyclicSwitchIn MC_CAMSWITCH_REF

Controls the switching actions.

  • TrackNumber: must be zero.
  • FirstOnPosition: must be nonnegative. It is the distance relative to the each cycle’s starting position.
  • LastOnPosition: must be positive and greater than FirstOnPosition. It is the distance to the each cycle’s starting position.
  • Duration: must be positive.
VAR_INPUT
V Enable BOOL

Enables a cyclical track.
V StartPosition LREAL The position from which the switch is on.
V IntervalType MC_LengthType The type of Interval. mcDistance and mcTime can be used.
V Interval LREAL The length of a cycle. It depends on the IntervalType you select. This value must be positive.
V DurationType MC_LengthType The type of Duration. mcDistance and mcCount can be used.
V Duration LREAL

the duration over which the cycle repeats. It depends on the DurationType you select. This value must be positive.
V ValueSource MC_Source

Defines the source for axis values. For example, positions:

  • mcCommandedValue, mcSetValue – synchronization on set value. We suggest you use these settings.
  • mcActualValue – synchronization on actual value. This setting may not be stable.
  • mcSecondEncoderValue – the actual value read from the second encoder.
VAR_OUTPUT
V Done BOOL The cyclical task is completed.
V Busy BOOL The function block is not finished and new output values are to be expected.
V Active BOOL The function block is controlling the axis.
V CommandAborted BOOL The command is aborted by another command.
V Error BOOL Signals that an error has occurred within the function block.
V ErrorID MC_Error Error identification.
  • MC_CAMSWITCH_REF is a vendor specific structure that defines switches for digital cam.
  • MC_OUTPUT_REF is a vendor specific structure linked to the (physical) outputs.
  • In the MC_CAMSWITCH_REF structure, when CamSwitchMode is Position, the following combinations are not supported:
    • IntervalType: mcTime, DurationType: mcDistance.
    • IntervalType: mcTime, DurationType: mcCount.

 

  MC_CyclicSwitch  
AXIS_REF   AxisIn   Axis   AXIS_REF
MC_OUTPUT_REF   OutputIn   Output   MC_OUTPUT_REF
MC_CAMSWITCH_REF   CyclicSwitchIn   CyclicSwitch   MC_CAMSWITCH_REF
BOOL   Enable   Done   BOOL
LREAL   StartPosition   Busy   BOOL
MC_LengthType   IntervalType   Active   BOOL
LREAL   Interval   CommandAborted   BOOL
MC_LengthType   DurationType   Error   BOOL
LREAL   Duration   ErrorID   MC_Error
MC_Source   ValueSource        
             

 

Use cases:

The following cases are in the RT/Win32 interface, but they help you understand how a cyclic switch work.

Case 1

A cyclic switch completes its task for the duration.

McOutput outputBit = {
   FALSE,   //Axis or IO module. FALSE = I/O.
   0,       //Index
   0        //Offset
}

McCamSwitch cyclicSwitch = {
   0,    //TrackNumber
   40,   //FirstOnPosition 
   60,   //LastOnPosition
   1,    //AxisDirection. 1 = Positive.
   0,    //CamSwitchMode. 0 = Position.
   0     //Duration. It is not used in this case.
);

Command = SetAxisCyclicSwitch(
   TargetAxis,    //Index
   outputBit,     //Output
   100,           //StartPosition
   cyclicSwitch,  //CyclicSwitch
   mcDistance,    //IntervalType
   100,           //Interval
   mcDistance,    //DurationType
   250,           //Duration
   mcSetValue     //ValueSource
);

Case 2

A cyclic switch is aborted before it completes the task.

McOutput outputBit = {
   FALSE,   //Axis or IO module. FALSE = I/O.
   0,       //Index
   0        //Offset
}

McCamSwitch cyclicSwitch = {
   0,        //TrackNumber
   0,        //FirstOnPosition
   0,        //LastOnPosition
   1,        //AxisDirection. 1 = Positive.
   1,        //CamSwitchMode. 1 = Time.
   0.003     //Duration
);

Command = SetAxisCyclicSwitch(
   TargetAxis,    //Index
   outputBit,     //Output
   100,           //StartPosition
   cyclicSwitch,  //CyclicSwitch
   mcTime,        //IntervalType
   0.005,         //Interval
   mcCount,       //DurationType
   3,             //Duration
   mcSetValue     //ValueSource
);