Rockwell Automation 8520 9/Series CNC Lathe User Manual

Page 208

Running a Program

Chapter 7

7-32

To perform a block retrace operation:

Press the

or activate the

feature

button to stop program execution.

Press the

button.

After you press the

button, the control retraces the block

that was being executed when the cycle stop occurred or retraces the block

just completed if you press the single block button, provided that the block

is a legal block for retrace.

While the block retrace function is active, the light in the

button is on. The block that was shown as active when

the block retrace was activated still appears as the currently active block in

the program display area during the entire use of the block retrace function.

Important: If you use the

button to halt execution to begin

a block retrace, the control re-executes the portion of the block that has

been executed. For example, if the block requests an axis move of 20 mm

and the axis has moved 12 mm when you press the

button, a

block retrace reverses the axis direction 12 mm.

All retraced blocks are executed at the feedrate programmed for that block

though this may be modified by the use of the

switch. See chapter 18.

Press the

button at any time during a block retrace to

return the cutting tool to normal forward execution. Program execution

returns to the normal forward direction from the currently retraced block.

The control executes the retraced blocks in normal order until the tool is

positioned at the start point of block retrace. From this point it continues

program execution in a normal fashion unless

is active.

is active, the control halts execution when the return

from block retract is complete.

While block retrace is active, the control disables all jog features with the

exception of

. See page 7-17. MDI is not available to

insert blocks during a block retrace operation.