MC_GrpReadCmdPos

Description

MC_GrpReadCmdPos fills the array (specified by the Position argument) with the commanded position of the coordinate system specified by the CoordSystemargument. 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 8-174: MC_GrpReadCmdPos

There is a one to one correspondence between the axes in the Axes Group and the position values in the Position Array. Each element in the Position Array corresponds to the axis element in the Axis Group array. If an index in the Axes Group is unassigned then the position value for that array element in the Position Array will be 0. If the element does contain an axis then the position value will be filled with the current actual position 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_GrpReadCmdVel

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 position of the axes in the group
	Data type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
AxesGroup	Description	The axes group from which the commanded position 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 position.
	Data type	SINT
	Range	One of the following enumeration values:  MC_COORDINATE_SYSTEM_ACS = 0 MC_COORDINATE_SYSTEM_MCS = 1 MC_COORDINATE_SYSTEM_PCS = 2
	Unit	N/A
	Default	—
Position[]	Description	An array where the position 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
	Default	—

Output

Valid	Description	If true, that the positions 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

Example

Structured Text

            (*MC_GrpReadCmdPos ST"Structured text"
A high-level language that is block structured and syntactically resembles Pascal example *)
Inst_MC_GrpReadCmdPos(DoRead, Group, CoordSys, PosList );

IL

            BEGIN_IL"Instruction list"
This is a low-level language and resembles assembly
            
     CAL Inst_MC_GrpReadCmdPos( DoRead, Group, CoordSys, PosList )
END_IL

FBD

FFLD

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