MC_GrpReadActVel

 Function Block - Reads the actual velocity of the group and the axes in the group.

• 
  
• • This function or function block returns cached data.
  • See Program a Multi-Core Controller.

• See Coordinated Motion, the top-level topic for Coordinated Motion.
• This function or function block does not generate any motion.
• See Function Blocks - General Rules about how inputs and outputs work.
• The MC_GrpReadActVel function block fills the array specified by the Velocity argument with the actual velocity of the system in the coordinate system specified by the CoordSystem argument.
  • The measured path velocity is also calculated and reported by the PathVelocity output.

• 
  
  

• • The actual velocity is averaged over the last 10 samples.
    • This reduces the error in velocity estimation but introduces a small amount of phase delay in the reported velocities.
  • Only the ACS coordinate system is supported.
    See Coordinate Systems.

• There is a one-to-one correspondence between the axes in the Axes Group and the velocity values in the Velocity Array.
• If a index in the Axes Group is unassigned, the velocity value for that array element in the Velocity array is 0 (zero).
• If the element does contain an axis, the velocity value is filled with the current actual velocity for that axis.
  • This is an example of how this works:
    

Inputs

Input	Data Type See Data Types.	Range	Unit	Default	Description
Enable	BOOL	FALSE, TRUE	N/A	No default	If TRUE, this function block reads the current actual velocity of the group and the axes in the group.
AxesGroup	AXES_GROUP_REF	N/A	N/A	No default	The axes group the actual velocity is read from.
CoordSystem	SINT	Enumerated	N/A	No default	The coordinate system used when reading the actual velocity. One of these enumeration values: Value Description CS_ACS Axes Coordinate System CS_MCS Machine Coordinate System CS_PCS Product Coordinate System
Velocity	LREAL[ ]	Dimension: The number of axes mapped in the AxesGroup. No range	User units / sec	No default	An array where the velocity data is written. The length of the array must equal the maximum number of axes allowed in the group. The maximum number of axes is an argument to the MC_CreateAxesGrp function block used to create axes groups.

Outputs

Output	Data Type See Data Types.	Range	Unit	Description
Valid	BOOL	FALSE, TRUE	N/A	If TRUE, the velocities were read without error.
Error	BOOL	FALSE, TRUE	N/A	If TRUE, an error has occurred.
ErrorID	INT	Enumerated	N/A	Indicates the error if Error output is TRUE. See PLCopen Function Block ErrorIDs.
PathVelocity	LREAL	No range	User units / sec	The current measured path velocity of the group. This is measured by taking the square root of the sum of the squared velocities of each axis.

FBD Language Example

FFLD Language Example

IL Language Example

Not available.

ST Language Example

Inst_MC_GrpReadActVel(DoRead, Group, CoordSys, VelList);

See Also

• MC_GrpReadActAcc
• MC_GrpReadActPos
• MC_GrpReadCmdPos
• MC_GrpReadCmdVel