Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 209)

Running a Program
Chapter 7
7-33
The block retrace function is unable to retrace any of these blocks and an
attempt to do so results in an error message:
Threading
Tapping
Boring
Inch/Metric changes (unit conversion)
A block that commands a tool change operation
A block that commands a change in the coordinate system
Any block that is followed by a Manual Jog Move except a Jog Retract
The number of blocks retraced is already equal to the maximum number
of retraceable blocks as determined in AMP
Certain Paramacro Parameter Assignments
Interrupt Macros
Any multiprogramming synchronization block (M100 -- M199)
CAUTION: If the block retrace function is deactivated during
its execution (performing a control reset, E-Stop, etc.),
attempting to return the tool by pressing cycle start can cause an
undesired return path. The tool returns to the start point of
block retrace along a linear path. This is most likely not the
retracted path. To avoid possible part or tool damage, we
recommend that the cutting tool be jogged to the point from
which block retrace was started prior to pressing cycle start.
Figure 7.7
Pressing Cycle Start When Retract Path is Lost
Block retrace
aborted here
Start point
of block
retrace
Normal block retrace path
Return path taken when
cycle start is pressed after
block retrace is aborted
END OF CHAPTER