Rockwell Automation MPMA Integrated Multi-Axis Linear Stages - Manual (Page 119)

Rockwell Automation Publication MPMA-UM001B-EN-P - November 2010 119
Home to Torque-level Example Appendix D
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 a fault 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 which 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 53 - 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 (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