Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 219)

Running a Program
Chapter 7
7-31
While block retrace is active, the control disables all jog features with the
exception of
<JOG RETRACT> . See page 7-27 for details on Jog Retract.
MDI is not available to insert blocks during a block retrace operation.
The block retrace function is unable to retrace any of the following blocks
and an attempt to do so results in an error message:
Thread grinding
Inch/Metric changes (unit conversion)
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 programs or interrupt dressing operations
ATTENTION: If the block retrace function is deactivated
during its execution (performing a control reset, E-Stop, etc.),
attempting to return the axis by pressing cycle start can cause an
undesired return path as shown in Figure 7.8. The axis returns
to the start point of the block retrace along a linear path that is
usually not the same as the retracted path. To avoid possible
part or wheel damage, jog the grinding wheel to the point from
which block retrace was started prior to pressing cycle start.
Figure 7.8
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
12012-I
END OF CHAPTER