Motion Block

Description

Set Commanded Position is used to set the desired setpoint for the motor. During normal profiled moves the commanded position is set by the internal motion profiler whilch calculates a smooth sequences of commanded positions. However there are some situations where the criteria for where the motor should move each sample period is custom, for example electronic gearing. Set Commanded Position bypasses the internal motion profiler allowing the direct assignment of the position setpoint. Note that a discontinuity in setpoint positions will directly map into an attempted discontinuity in motor position resulting in a substantial bump. When working with stepper motors Set Commanded Position must be used along with Set Profile Velocity to accomplish effective motion performance. This command is usually used in a resident program operating at the sample rate frequency necessry to provide a smooth trajectory.

Querying the commanded position reports the intended position for the motor. Virtual axes can only report commanded positions as there is no actual position with a virtual axis. Commanded motion can occur on a physical axis with the motor off.

The Commanded Position of a coordinated group is the pathlength along the vector move.

Escapes

The Set Commanded Position command does not generate any escapes.

Examples

This block list performs electronic gearing. Note that PositionNM1 (N minus 1) is used instead of PositionN for Set Commanded Position because of how the controller integration works.

Related Topics

Commanded Position
Positive Limit
Negative Limit
Actual Position
Destination Position