XFC_BreakCam

XFC_BreakCam realizes a brake cam, which deactivates a digital output depending on the position as soon as BreakRelease is withdrawn.

In addition to the switching state of the digital output the output data structure contains precise time information for the next switching operations. This information is used for the actual output at an XFC output terminal with a downstream function block (XFC_EL2252 or XFC_EL2262).

Inputs

VAR_INPUT
    BreakRelease    : LREAL;
    LastOnPosition  : LREAL;
    Modulo          : BOOL;
    ModuloFactor    : LREAL := 360;
    OffCompensation : LREAL;
    Options         : ST_CamSwitchOptions;
END_VAR

BreakRelease	Brake enable. The cam remains active as long as BreakRelease is TRUE. When BreakRelease becomes FALSE, the cam is switched off at position LastOnPosition.
LastOnPosition	Last position up to which the cam is switched on.
Modulo	If Modulo TRUE, all positions are interpreted as modulo. The cam function is repeated cyclically. The parameter ModuloFactor is used for calculating the modulo cycle.
ModuloFactor	ModuloFactor indicates the length of a modulo cycle in the positioning unit of the axis and is only used if Modulo=TRUE.
OffCompensation	Compensation time for the falling edge of the cam in [s]. For negative values of OnCompensation the switching time is brought forward, otherwise it is delayed. The value OffCompensation parameterized here has priority over TRACK_REF.
Options	Optional parameters
Options.	EncoderIndex	If more than one encoder is connected to the axis, the encoder index can be defined here.
Options.	UseAcceleration	UseAcceleration can be set to TRUE in order to incorporate the acceleration of the axis into the position calculation. UseAcceleration can be advantageous if the setpoint values of the acceleration can be used. UseAcceleration may be disadvantageous with encoder axes that supply a noisy position signal, because the acceleration is also erroneous.

Inputs/outputs

VAR_IN_OUT
    Output : OUTPUT_REF; 
    Axis   : AXIS_REF; 
END_VAR

Output	The data structure Output contains the calculated state of the digital output and the associated time stamp for the output at a digital XFC output terminal.
Axis	Axis data structure

The axis data structure of type AXIS_REF addresses an axis uniquely within the system. Among other parameters it contains the current axis status, including position, velocity or error status.

Method of function of the time compensation