Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 351)

Overtravels and Programmable Zones
Chapter 12
12-13
The control stops tool motion during overtravel conditions. Overtravel
conditions may occur from 3 causes:
hardware overtravel -- the axes reach a travel limit, usually set by a
limit switch or sensor mounted on the axis. Hardware overtravels are
always active.
software overtravel -- commands cause the axis to pass a software
travel limit. Software overtravels are active only after the axis has been
homed provided the feature has been activated in AMP by the system
installer.
Programmable Zone Overtravel -- The tool reached a travel limit
established by independent programmable areas. Programmable Zones
are activated through programming the appropriate G code.
In all cases, the control issues an error message.
When an overtravel condition occurs, all axis motion is forced to a stop,
the control is placed in cycle stop and one of the following applicable error
messages is displayed.
Where : Is :
“HARDWARE OVERTRAVEL (-) BY AXIS (X)” This message indicates that the specified axis has
tripped either the + or - hardware limit switch
mounted on the machine.
“SOFTWARE OVERTRAVEL (+) BY AXIS (X)” This message indicates that the specified axis has
entered the overtravel area defined by the softlimits
in either a positive or negative direction.
“VIOLATION OF ZONE (2) BY AXIS (X)” This message indicates that a tool has reached the
specified axis overtravel area defined by either
programmable zone 2 or 3.
When an overtravel of any type has taken place, axis feed in the same
direction as the feed causing the overtravel is not allowed. Only axis feed
in the reverse direction is possible.
How a hardware overtravel condition is reset depends on the ESTOP
circuit design and the way PAL was programmed by the system installer.
12.5
Resetting Overtravels