Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 213)

Running a Program
Chapter 7
7-31
Figure 7.7
Jog Retract Moves that Exceed the Maximum Allowed in AMP
1
2
3
4
5
6
7
Return path
Figure 7.7 emphasizes the possible problems that may result from
exceeding the maximum allowed jog retract moves. In this example the
number of allowed moves set in AMP is four.
When the cycle start button is pressed at the end of the 7th jog move the
control ignores moves 5, 6, and 7 and takes the shortest path to the
endpoint of exit move 4. This is because the maximum number of jog
retract moves set in AMP has been exceeded. After reaching the endpoint
of move 4 the control continues the jog retract return operation as normal.
If the jogging moves of 5, 6, and 7 were intended to avoid a protrusion
during the jog retract, a collision could result when returning the tool.
The block retrace function allows the operator to retrace the motion created
by up to 15 consecutive part program blocks. The actual number of retrace
blocks allowed is set by the system installer in AMP, and may vary from 1
to 15.
Important: For maximum control efficiency when executing programs it
is recommended that the maximum number of allowable block retraces is
set as small as possible for the current machine application. This is
because the number of allowable Block Retraces directly effects the
controls block look ahead operation.
This function can only be enabled when the control is in cycle stop or
cycle suspend state and is ignored if the control has already executed an
M02 or M30 end of program.
7.10
Block Retrace