Table of Contents

Cycle Integration

This guide focuses on how to integrate Struckig into a PLC task loop safely and predictably.

Use a stable three-part cycle:

  1. update targets and limits at well-defined step boundaries
  2. call otg() exactly once per PLC cycle
  3. map outputs to axis setpoints and handle state/errors
// 1) Update targets on sequence events (not shown here)

// 2) Cyclic update
otg();

// 3) Output mapping and safety checks
IF otg.State = Struckig.TrajectoryState.Error THEN
  Abort(otg.ErrorMessage());
ELSE
  axisX.SetInterpolatedPosition(THIS^, otg.CurrentPosition[0]);
  axisY.SetInterpolatedPosition(THIS^, otg.CurrentPosition[1]);
  axisX.SetInterpolatedVelocity(THIS^, otg.CurrentVelocity[0]);
  axisY.SetInterpolatedVelocity(THIS^, otg.CurrentVelocity[1]);
END_IF

Task cycle time

  • Set cycletime to the real PLC task period in seconds.
  • If task time changes dynamically, update CycleTime before running otg().
  • Keep jitter low in motion tasks to avoid setpoint quality degradation.

State handling

Typical state flow:

  • Busy: trajectory is active
  • Idle: target reached within internal checks
  • Error: invalid input or infeasible constraints

Use transitions on Idle to trigger the next machine step.

Important nuance:

  • Idle means final target state is reached.
  • If target velocity or acceleration is non-zero, physical movement can still be expected in downstream drive behavior even when the trajectory state is complete for the requested target.

Target update timing

Do:

  • write complete target vectors atomically at step entry
  • reset current state only when starting a new independent segment

Avoid:

  • partial per-element target updates across multiple cycles
  • changing hard limits continuously unless this is a deliberate feature

Input validation flow

Before applying new targets from external logic, validate input:

IF NOT otg.ValidateInput(
  checkCurrentStateWithinLimits := FALSE,
  checkTargetStateWithinLimits := TRUE
) THEN
  Abort(otg.ErrorMessage());
END_IF

This catches invalid values earlier and gives better diagnostics than handling errors only after otg().

Multi-axis notes

  • Keep all axis constraints in realistic mechanical range.
  • Use Phase synchronization for coordinated path execution.
  • Use TimeSync for simultaneous arrivals with less strict geometric coupling.
  • Use None when independent axis completion is preferred, for example emergency deceleration behavior.

Per-DoF runtime control

You can mix interfaces or synchronization modes per axis:

otg.ControlInterface := Struckig.ControlInterfaceType.Position;
otg.PerDofControlInterface[1] := Struckig.ControlInterfaceType.Velocity;

otg.Synchronization := Struckig.SynchronizationType.TimeSync;
otg.PerDofSynchronization[2] := Struckig.SynchronizationType.None;

Use this carefully, as mixed policies can change trajectory shape and duration in non-obvious ways.

Integration checklist

  • cycletime matches task period
  • consistent units across all vectors
  • one otg() call per cycle
  • explicit Error handling path
  • axis outputs mapped every cycle
  • ValidateInput is used at setpoint handover boundaries
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