Rockwell-automation MPAS Integrated Linear Stages User Manual download pdf (Page 95)

Rockwell Automation Publication MP-UM001D-EN-P - September 2013 95

Home to Torque-level Example Appendix E

Disable Soft Overtravel

Limit

If the application requires the use of soft-overtravel limits (Limits tab) to

safeguard the system mechanics, disable the Soft Travel Limits for the axis to

home. The Soft Travel Limits are disabled to prevent an error from occurring

during the homing operation, but re-enable them after homing completes.

Ladder Code Example

This example shows how to adjust the peak torque limit and disable the soft-

overtravel limit checking when homing to a torque limit. The code uses a state

model methodology in that each rung of code needs to complete successfully

before moving to the next rung.

Rung 11 of the ladder code checks to make sure that the axis position, after

homing, is within the Soft Travel Limits before re-enabling soft-overtravel limit

checking. In this example a 1.15 cm Offset move is configured in the Homing tab

and that is the final home position. The 0.5 cm is within the Soft Travel Limits

set on the Limits tab.

Table 17 - Tags Used

IMPORTANT

Those responsible for the application must determine when it is

safe and appropriate to disable soft-overtravel checking.

IMPORTANT

Because the home to torque-level sequence relies on the

mechanical end of travel for operation, Uni-directional homing is

not possible. You must choose between Forward Bi-directional or

Reverse Bi-directional.

Tag Name Data Type Description

Saved_FaultConfig DINT Storage location for FaultConfigurationBits (motion attributes)

Bit 0 = soft-overtravel limit checking

Clear_SoftOT_Mask DINT Set to -2.

This masks the off soft-overtravel enable bit without changing the other configuration bits.

Temp_FaultConfig DINT Temporary hold word for FaultConfigurableBits

SoftOT_Disabled BOOL Soft-overtravel checking disabled status bit

Saved_TQLim_Bipolar REAL Storage location for Peak Torque (TorqueLimitBipolar)

HomeTQ_Level REAL Home Torque Level from the Home tab in Axis Properties

Temp_TQLim_Bipolar REAL Temporary Peak Torque for Homing (10% higher than Home Torque Limit)

Axis_01_MI.MAH MOTION_INSTRUCTION Control for MAH instruction (by using a UDT)

Positive_Overtravel REAL Max Positive Soft-overtravel value

Negative_Overtravel REAL Max Negative Soft-overtravel value

Saved_PosErrorTol REAL Storage location for Actual Position Error value

Temp_PosErrorTol REAL Temporary Position Error value for Homing

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Rockwell-automation MPAS Integrated Linear Stages User Manual Page 95