Function BlockMC_StopPLCopen motion icon

Description

This function block aborts the active move, removes the next move from the queue, performs a controlled stop at the specified deceleration rate, and switches the axis to Stopping state.

MC_Stop cannot be aborted. This means that, while in Stopping state, no function block can command any motion on the axis. The axis remains in Stopping state until it reaches zero velocity and the Execute input is low. The application program can hold the axis in Stopping state even after it reaches zero velocity by leaving the Execute input high.

MC_Stop

Figure 7-121: MC_Stop

Time Diagram

The example below shows the behavior of the combination of a MC_Stop FB with a MC_MoveVelocity FB.

  • A rotating axis is ramped down with FB2 MC_Stop
  • The axis rejects motion commands as long as MC_Stop parameter “Execute” = TRUE

FB1 MC_MoveVelocity reports an error indicating the busy MC_Stop command.

MC_Stop: Timing Diagram

Arguments

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

Input

Execute Description Requests to stop the axis.
It can be held high to prevent any other moves from being queued
  Data type BOOL
  Range 0, 1
  Unit N/A
  Default
Axis 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
Deceleration Description Trapezoidal: Deceleration rate
S-curve: Maximum deceleration
  Data type LREAL
  Range
  Unit User unit/sec2
  Default
JerkClosedIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time Description Trapezoidal: 0
S-curve: Constant jerkClosedIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time
  Data type LREAL
  Range
  Unit User unit/sec3
  Default

Output

Done Description Indicates the axis has reached zero velocity AND the Execute input is low
  Data type BOOL
Busy Description High from the time the Execute input goes high until the axis reaches zero velocity AND the Execute input is low
  Data type BOOL
Active Description High from the time the MC_Stop move becomes the active move, until the axis reaches zero velocity AND the Execute input is low
  Data type BOOL
Error Description Indicates an invalid input was specified
  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_Stop S
            T example *)

Inst_MC_Stop( StopRequest , Axis1, 100.0, 100.0 ); //Inst_MC_Stop is an instance of MC_Stop function block


StopComplete := Inst_MC_Stop.Done;     //store the Done output into a user defined variable

StopActive := Inst_MC_Stop.Active;     //store the Active output into a user defined variable

StopError := Inst_MC_Stop.Error;       //store the Error output into a user defined variable	

Ladder Diagram

MC_Stop: LD example

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