MC_DigitalCamSwitch (FB)

FUNCTION_BLOCK MC_DigitalCamSwitch

This function block is analogous to switching on a motor shaft: The function block commands a group of discrete output bits to switch in analogy to a set of mechanical cam controlled switches connected to an axis. Forward and backward movements are allowed.

Note

Changing the VAR_IN_OUT-parameters requires a new rising edge of the Enable input.

Notice

This functionality is sometimes called PLS – Phase or Position or Programmable Limit Switch.

Example

Assume the following parameter values set:

Parameter	Type	Switch01	Switch02	Switch03	Switch04
TrackNumber	INT	1	1	1	2
FirstOnPosition [u]	REAL	2000	2500	4000	3000
LastOnPosition [u]	REAL	3000	3000	1000	-
AxisDirection	INT	1=Pos	2=Neg	0=Both	0=Both
CamSwitchMode	INT	0=Position	0=Position	0=Position	1=TIME
Duration	TIME	-	-	-	1350

Assume further, that no on/off compensation nor hysteresis is employed. The figure demonstrates the behavior of the outputs, when the axis is moving continuously in positive direction. The axis is a modulo axis with a modulo length of 5000 u.

Example of DigitalCamSwitch

Now assume that on compensation (-125ms) and off compensation (+250ms) are employed.

Detailed description of Switch01

The resulting behavior of the outputs, when the axis is moving continuously in negative direction without on/off compensation and without hysteresis.

Example in negative direction

InOut:

Scope	Name	Type	Initial	Comment
Inout	Axis	AXIS_REF_SM3		Reference to axis the switches are connected to
	Switches	MC_CAMSWITCH_REF		Reference to switching actions
	Outputs	MC_OUTPUT_REF		Reference to signal outputs that are directly related to the referenced tracks
	TrackOptions	MC_TRACK_REF		Reference to structure containing track related properties, e.g. the on/off compensations per output/track.
Input	Enable	BOOL	FALSE	TRUE: Enables execution of function block.
	EnableMask	DWORD	16#FFFFFFFF	32 bits of BOOL enabling the different tracks. Least significant data is related to the lowest TrackNumber.
	TappetMode	MC_TAPPETMODE	tp_mode_auto	Mode for position outputs
Output	InOperation	BOOL	FALSE	TRUE: Commanded tracks have been enabled.
	Busy	BOOL	FALSE	TRUE: Execution of function block has not been finished yet.
	Error	BOOL	FALSE	TRUE: Error has occurred within the function block.
	ErrorID	SMC_ERROR	0	Error identification
	SwitchCorrupted	INT		Signalizes potential problems that arise from compensation times: Compensation times may lead to the case that the extrapolated position passes one switching point several times before passing the other switching point again. As a consequence, a non-inverted switch may become inverted (and the other way around). In this case, this variable indicates the switch in concern. There are two possible reasons: noisy velocity-values, "big" difference between on- and off-compensation. -1 means that such behaviour hasn't occured.

MC_DigitalCamSwitch.CheckHysteresis (ACT)

MC_DigitalCamSwitch.InitSwitch (ACT)