MC_GrpReadActAcc

 Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Reads the actual acceleration A change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, acceleration is the rate at which something speeds up or slows down. However, more generally, acceleration is a vector quantity expressing the change with time of the velocity both in magnitude and in direction. See these Wikipedia articles for more information: http://en.wikipedia.org/wiki/Velocity http://en.wikipedia.org/wiki/Euclidean_vector http://en.wikipedia.org/wiki/Rate_(mathematics) of the group and the axes in the group.

Inputs

Input	Data Type	Range	Unit	Default	Description
Enable Enable signal for the drive, Hardware-Enable with 24V signal to X8, Software-Enable command by setup Software, fieldbus or permanently set. Both are required for enabling the drive.	BOOL	FALSE, TRUE	N/A	No default	If TRUE, this function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. block reads the current actual acceleration of the group and the axes in the group.
AxesGroup	AXES_GROUP_REF	No range	N/A	No default	The axes group the actual acceleration is read from.
CoordSystem	SINT	One of these enumeration values: MC_COORDINATE SYSTEM The reference system in which a coordinate or path is described._ACS Axes Coordinate System - The system of coordinates related to the physical motors and the single movements caused by the single drives. = 0 MC_COORDINATE_SYSTEM_MCS = 1 MC_COORDINATE_SYSTEM_PCS Product Coordinate System or Program Coordinate System. The PCS is based on the MCS by shifting and maybe rotating the MCS. The Zero point of the PCS is related to the product and can be changed during runtime by the program. The real work piece can have a rotation or shift to the MCS coordinate system or even might be moving relative to the MCS coordinate system. By specifying a trajectory in PCS one is able to describe the trajectory independent from the machine situation. To map these two worlds (MCS to PCS and vice versa), a Cartesian or cylindrical transformation is normally done. = 2	N/A	No default	The coordinate system used when reading the actual acceleration.
Acceleration[ ]	LREAL	No range	User unit/sec2	No default	An array where the acceleration 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	Range	Unit	Description
Valid	BOOL	FALSE, TRUE	N/A	If TRUE, the accelerations have been read without error.
Error	BOOL	FALSE, TRUE	N/A	If TRUE, an error has occurred.
ErrorID	INT			Indicates the error if Error output is TRUE. See PLCopen Function Block ErrorIDs.
PathAcceleration	LREAL		User unit/sec2	The current measured path Set of continuous positions and orientation information in multi-dimensional space. Geometrical description of a space curve that the TCP of an axesgroup moves along. acceleration of the group. This is measured by taking the square root of the sum of the squared accelerations of each axis.

Remarks

• 
  

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

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

• 
  

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

• There is a one-to-one correspondence between the axes in the Axes Group array and the acceleration values in the Acceleration array.
• Each element in the Acceleration array corresponds to the axis element in the Axes Group array.
• If an index Zero pulse (zero signal) of a hardware pin such as digital input or feedback pin. in the Axes Group is unassigned, the acceleration value for that array element in the Acceleration array is 0 (zero).
• If the element does contain an axis, the acceleration value is filled with the current actual acceleration for that axis.
  • This is an example of how this works:
    

Figure 1: MC_GrpReadActAcc

FBD Language Example

FFLD Language Example

IL Language Example

            BEGIN_IL Instruction list - This is a low-level language and resembles assembly.
     CAL Inst_MC_GrpReadActAcc( DoRead, Group, CoordSys, AccList )
END_IL

ST Language Example

Inst_MC_GrpReadActAcc( DoRead, Group, CoordSys, AccList );

See Also

• MC_GrpReadActPos
• MC_GrpReadActVel
• MC_GrpReadCmdPos
• MC_GrpReadCmdVel