# MC_MoveAbsolute

A motion of the axis to an absolute position is commanded by the FB MC_MoveAbsolute. The motion is always executed jerk-limited at constant jerk set in "Jerk”. This value is valid for both "Acceleration" and “Deceleration”.

If the optional parameters “Acceleration, “Deceleration” and “Jerk” are not specified or set to <= 0, the dynamic values are taken from the corresponding axis list.

Block diagram

FB parameters

VAR_IN_OUT
Variable name | Data type | Description
Axis | AXIS_REF | Axis reference

VAR_INPUT
Variable name | Data type | Description
Execute | BOOL | A rising edge at the input commands the motion to an absolute position.
Position | LREAL | Target position of the motion, Value range [-2147483648.0, 2147483647.0] Default unit [0.1µm or 10-4 °]
Velocity | LREAL | Maximum velocity of the motion. This value must be specified positive. The velocity is not necessarily reached. Value range [1.0, 2147483647.0] Default unit [1µm/s or 10-3 °/s]
Acceleration | LREAL | Acceleration value. This value must be specified positive. Value range [0.0, 2147483647.0] Default unit [1mm/s2 or 1°/s2]
Deceleration | LREAL | Deceleration value. This value must be always be specified positive. Value range [0.0, 2147483647.0] Default unit [1mm/s2 or 1°/s2]
Jerk | LREAL | Jerk value. This value must be always be specified positive. Value range [0.0, 2147483647.0] Default unit [1mm/s3 or 1°/s3]
Direction | INT | Direction in which the motion is started. One of the 4 values: 1 positive direction 2 shortest path 3 negative direction 4 current direction

Specifying the direction is effective only if a modulo coordinate system was defined for the axis in the axis-specific machine data using parameter kenngr.achs_mode (P-AXIS-00015) since the direction is always unambiguous with linear axes.

VAR_OUTPUT
Variable name | Data type | Description
Done | BOOL | The axis is within a range close to the target position. The range is specified by the parameter getriebe[...].window (P-AXIS-00236) of the axis-specific machine data.
CommandAborted | BOOL | TRUE indicates that the command was aborted by another command.
Error | BOOL | Is TRUE if an error occurs in the FB.
ErrorID | WORD | Error identifier

Behaviour of the FB:

- This motion is commanded only when the axis is in the “Standstill” or “Continuous Motion” or “Discrete Motion” or “Synchronised Motion” state. If this is not the case, the error output is set to “FALSE and “ErrorID” indicates an error value that designates the state the axis is currently in.
- The “Position, “Velocity, “Acceleration”, “Deceleration” and “Jerk” input variables are monitored only for their value range in the FB. If the values are exceeded, an error number referring to the variable is output at the “ErrorID” output and “Error” is set to TRUE. Moreover, the maximum velocity and acceleration data is limited within the motion controller. If speed values greater than getriebe[0].dynamik.vb_max (P-AXIS-00212) or acceleration or deceleration values greater than getriebe[0].dynamik.a_max (P-AXIS-00008) are commanded, the motion takes place nevertheless. However, the values are limited to the parameterised values and the motion controller issues a warning P-ERR-60211 or P-ERR-60188 to P-ERR-60194.
- Values for jerk are practical when they correspond to a minimum ramp time of TA (cycle time of the IPO, e.g. 2 ms) and a maximum ramp time of 100s. The limit transition to non-jerk-limited velocity control lies at the minimum ramp time of TA. With a value of 0, the maximum ramp time from the axis MDS is used to determine the jerk.
- This function block replaces active commands with new commands, making the function block retriggerable. The active command is then aborted.
- If an unreferenced axis is commended by this FB, the axis does not start. The error P-ERR-60142 is reported on the “MC_ReadAxisError” function block.
- The positions of the software limit switches (kenngr.swe_pos (P-AXIS-00178), kenngr.swe_neg (P-AXIS-00177), kenngr.swe_toleranz (P-AXIS-00179)) are monitored if the axis was defined either as a linear or a rotary axis. This means that the kenngr.achs_typ parameter of the axis machine data (P-AXIS-00018) has the value 0x0001 or 0x0002. If the target position commanded exceeds the position of the software limit switches, the axis starts off nevertheless. If a software limit switch position is reached, the axis is braked, keeping to the defined acceleration.