MC_GearIn

Description

This function block performs a slave axis move which follows the master axis based on the ratio specified by RatioNumerator and RatioDenominator.

SlaveCommandPosition = MasterActualPosition * RatioNumerator / RatioDenominator

When this command is executed, the slave axis accelerates or decelerates (using the Acceleration, Deceleration, and JerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time) to the target velocity determined by the master axis velocity and the ratio. When the slave axis reaches a velocity within the “In Gear” bandwidth around the target velocity, it locks on to the master, and the InGear output goes high. When the slave is locked to the master, the slave motion is no longer affected by the acceleration, deceleration, and jerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time inputs.

For example if the “In Gear” bandwidthIn computer networking, bandwidth often refers to a data rate measured in bits/s, for example, network throughput. The reason for the connection of data rate with the term bandwidth is that the limit to the data rate of a physical communication link is related to its bandwidth in hertz is set to 0.1 User Units per second, the InGear output will turn on if the slave velocity is within +/- 0.1 User Units per second of the target velocity.

The slave axis then continues to follow the master axis until this move is aborted.

Aborting Gearing

Gearing functions can generate large accelerations while following the master. If the aborting function block has small, non-zero Jerk, or small acceleration values, it can take a long time for an accelerating axis to reach the target velocity, or position of the aborting function block. If the Jerk and/or acceleration of the aborting function cannot be increased to suitable values, it may be desirable to:

• Abort the gearing function with an MC_GearOut with higher accelerations and/or Jerk values (or zero jerk value),
• Execute the next MC motion function block such as MC_Halt.

Time to Reach the Target Velocity

While following the master, gearing functions can generate large accelerations. If the gearing function is aborted while the axis is currently accelerating, and the aborting function block has small non-zero Jerk or small acceleration values, it can take a long time to reach the target velocity, or position of the aborting function block. If the Jerk and/or acceleration of the aborting function cannot be increased to suitable values, it may be desirable to:

• Abort the gearing function with an MC_GearOut with higher accelerations and/or Jerk values (or zero jerk value),
• Execute the next MC motion function block such as MC_Halt.

Figure 7-143: MC_GearIn

Time Diagram

• 
  
• This function block starts a motion-related action and therefore stores data for calculations and error checking. Please see Calling Function Blocks Multiple Times in the Same Cycle if you are using a dual-core controller.

Arguments

For more detail on how inputs and outputs work, refer to PLCopen Function Blocks - General Rules

Input

Execute	Description	Requests to queue the slave gear ratio move
	Data type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
Master	Description	Name of a declared instance of the AXIS_REF library function (for more details,About Axis Name and Number)
	Data type	AXIS_REF
	Range	[1,256]
	Unit	N/A
	Default	—
Slave	Description	AXIS_REF.AXIS_NUM is the slave axis number
	Data type	AXIS_REF
	Range	[1,256]
	Unit	N/A
	Default	—
RatioNumerator	Description	Numerator of master/slave ratio
	Data type	DINT
	Range	[-2147483648, 2147483647]
	Unit	N/A
	Default	—
RatioDenominator	Description	Denominator of master/slave ratio
	Data type	DINT
	Range	[-2147483648, 2147483647]
	Unit	N/A
	Default	—
Acceleration	Description	Trapezoidal: Acceleration rate S-curve: Maximum acceleration
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
Deceleration	Description	Trapezoidal: Deceleration rate S-curve: Unused
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
Jerk	Description	Trapezoidal: 0 S-curve: Constant jerk
	Data type	LREAL
	Range	—
	Unit	User unit/sec3
	Default	—
BufferMode	Description	0 = abort 1 = buffer See table in Buffer Modes
	Data type	SINT
	Range	[0,1]
	Unit	N/A
	Default	—

Output

InGear	Description	Indicates the slave axis is locked on to the master axis
	Data type	BOOL
Busy	Description	High from the moment the Execute input goes high until the time the move is ended
	Data type	BOOL
Active	Description	Indicates this move is the Active move
	Data type	BOOL
CommandAborted	Description	Indicates the move was aborted
	Data type	BOOL
Error	Description	Indicates an invalid input was specified or the move was terminated due to an error
	Data type	BOOL
ErrorID	Description	Indicates the error if Error output is set to TRUE See table in PLCopen Function Block ErrorID Output
	Data type	INT

Example

Structured Text

(* MC_GearIn ST example *)
   Inst_MC_GearIn( GearInReq, Axis1, Axis2, 2, 1, 150.0, 150.0, 0, 0 );
//Inst_MC_GearIn is an instance of MC_GearIn

See also how this function is used in the Hole punch project here

Ladder Diagram

 [Top]