Fixed Stop

Overview

This feature allows the user to move the axis to a fixed stop and exert a specified torque against it. Various status flags indicate when the fixed stop has been reached, passed or the axis is slipping. While a fixed stop motion task is running, the current is limited to the MT.FIXEDSTOPCURRENT. Faults related to fixed stop can be configured to trigger different drive reactions.

Configuring a Fixed Stop

A motion task can be configured to detect a fixed stop. The following parameters must be configured along with any standard motion task configuration (Motion Tasks). These parameters can be configured from the Terminal window in WorkBench.


  • The drive must be in position mode (DRV.OPMODE) to perform a fixed stop.

  1. MT.CNTL: Configure Bit 17 to activate fixed stop detection.
  2. MT.FIXEDSTOPFOLLOWINGERROR: When the actual following error (PL.ERR) reaches this parameter value, the fixed stop is registered. The end motion task position (MT.P) must be greater than MT.FIXEDSTOPFOLLOWINGERROR to ensure that the motion task reaches the fixed stop.
  3. MT.FIXEDSTOPMONITORWINDOW: When the fixed stop is reached, its position is monitored by a fixed stop window. If the actual position is out of this window, the fixed stop has broken off and fault 176 is triggered. Configure FAULT176.ACTION to determine whether the fault returns a fault, warning, or whether the fault is ignored.
  4. MT.FIXEDSTOPCURRENT: The current applied to the axis when a fixed stop has been reached. While a fixed stop motion task is running, the current limit (IL.LIMITP or IL.LIMITN depending on direction) will be overwritten by the value of MT.FIXEDSTOPCURRENT. Once the motion task has completed, the current limit is restored to its previous value.

  • Do not configure a following motion task for a fixed stop motion task.

That status of a fixed stop can be read from DRV.MOTIONSTAT.

DRV.MOTIONSTAT Bit Description
18 The fixed stop has been reached.
19

The fixed stop has been passed.

The motion task ended without triggering a fixed stop because the following error was lower than MT.FIXEDSTOPFOLLOWINGERROR.

This triggers Fault 178.
20

The axis broke off of the fixed stop position.

This triggers Fault 176.