MC_GearInPos (FB)

FUNCTION_BLOCK MC_GearInPos

MC_GearInPos couples the slave axis to the master axis taking into account a specific positional relationship.

Important

In certain cases, it may be impossible to avoid a reversal of the slave. (Even if the slave velocity is not opposite to the master.) One example is a slave with a small positive velocity and a large negative acceleration. It may not be possible to ramp down the acceleration fast enough to prevent the velocity from becoming negative.

Timing diagram

Any previous motion is continued until the master crosses the position MasterSyncPosition – MasterStartDistance in the correct direction. At that point in time the output StartSync is set. When a stop command is executed on the slave axis before the synchronization has happened, it will inhibit the synchronization and the function block issues CommandAborted is TRUE.

If the MasterStartDistance is not specified, the system itself calculates the setting point for StartSync based on the other relevant inputs.

Timing Diagram of MC_GearInPos

Different examples of gearing

InOut:

Scope	Name	Type	Initial	Comment
Inout	Master	AXIS_REF_SM3		Reference to master axis
Inout	Slave	AXIS_REF_SM3		Reference to slave axis
Input	Execute	BOOL		Rising edge: Starts the execution of the function block.
	RatioNumerator	DINT	1	Gear ratio numerator
	RatioDenominator	DINT	1	Gear ratio denominator
	MasterSyncPosition	LREAL		Master position where the axes run in sync.
	SlaveSyncPosition	LREAL		Slave position where the axes run in sync.
	MasterStartDistance	LREAL		Master distance for the gear in procedure (where the slave axis will be started for getting into synchronization). In other words, the slave is brought into sync with the master during this distance, i.e. from MasterSyncPosition - MasterStartDistance until MasterSyncPosition. If MasterStartDistance is 0 (or negative), then the slave movement is started immediately.
	AvoidReversal	BOOL		FALSE: Signals that the reversal of the slave is physically possible and acceptable. TRUE: Signals that the reversal of the module slave is physically impossible or might lead to damage. It works only with modulo slave axes. If a reversal cannot be avoided, the axis is stopped with an error. Behavior: If the slave axis is a modulo axis and the master velocity (times the sign of the gear ratio) is not opposite to the slave velocity, then MC_GearInPos tries to avoid a reversal of the slave. It tries to "stretch" the slave movement by increasing the distance the slave travels by up to 5 slave periods. If this "stretching" is not successful, an error is reported. If the slave velocity is opposite to the master velocity (times the sign of the gear ratio), an error is reported. If the slave axis is not a modulo axis, an error is reported on the rising edge of the Execute input.
Output	StartSync	BOOL		TRUE: Commanded gearing has been started.
	InSync	BOOL		TRUE: Cmmanded gearing has been completed.
	Busy	BOOL		TRUE: Execution of the function block has not been finished.
	CommandAborted	BOOL		TRUE: Command has been aborted by another command.
	Error	BOOL		TRUE: Error has occurred within the function block.
	ErrorID	SMC_ERROR		Error identification