MC_GrpReadCmdVel
Description
MC_GrpReadCmdVel fills the array specified by the Velocity
argument with the commanded velocity for the coordinate system, which is specified by the CoordSystem
argument. The path velocity is also reported via the ‘PathVelocity’ output. This function block does not cause any motion.
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Currently, only the ACS coordinate system is supported. See Coordinate Systems to learn more.
Figure 7-175: MC_GrpReadCmdVel
There is a one to one correspondence between the axes in the Axes Group and the velocity values in the Velocity Array. Each element in the Velocity Array corresponds to the axis element in the Axis Group array. If an index in the Axes Group is unassigned then the velocity value for that array element in the Velocity Array will be 0. If the element does contain an axis then the velocity value will be filled with the current velocity for that axis. Here is an example to illustrate how this works:
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This function or function block returns cached data. See Programming a Dual Core Controller for more information.
Related Function Blocks
MC_GrpReadActPos, MC_GrpReadActVel, MC_GrpReadActAcc, MC_GrpReadCmdPos
Coordinated Motion, the top-level topic for Coordinated Motion.
Arguments
For more detail on how inputs and outputs work, refer to PLCopen Function Blocks - General Rules.
Input
Enable | Description | If True, then this function block will read the current commanded velocity of the group and the axes in the group |
Data type | BOOL | |
Range | 0, 1 | |
Unit | N/A | |
Default | — | |
AxesGroup | Description | The axes group from which the commanded velocity will be read. |
Data type | AXES_GROUP_REF | |
Range | N/A | |
Unit | N/A | |
Default | — | |
CoordSystem | Description | The coordinate system used when reading the commanded velocity. |
Data type | SINT | |
Range |
One of the following enumeration values:
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Unit | N/A | |
Default | — | |
Velocity[] | Description | An array where the velocity data will be 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 MC_CreateAxesGrp, which is used to create axes groups. |
Data type | LREAL | |
Range | N/A | |
Unit | User units per second | |
Default | — |
Output
Valid | Description | If true, that the velocities have been read without error. |
Data type | BOOL | |
Error | Description | If true, an error has occurred. |
Data type | BOOL | |
ErrorID | Description | Indicates the error if Error output is set to TRUE. See the table in PLCopen Function Block ErrorID Output |
Data type | INT | |
PathVelocity | Description | The current commanded path velocity of the group, measured by taking the square root of the sum of the squared velocities of each axis. |
Data type | LREAL | |
Unit | User units per second |
Example
Structured Text
(*MC_GrpReadCmdVel ST"Structured text"
A high-level language that is block structured and syntactically resembles Pascal example *)
Inst_MC_GrpReadCmdVel(DoRead, Group, CoordSys, VelList );
IL
BEGIN_IL"Instruction list" This is a low-level language and resembles assembly
CAL Inst_MC_GrpReadCmdVel( DoRead, Group, CoordSys, VelList )
END_IL
FBD
FFLD