Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 670)

Skip and Gauge Probing Cycles
Chapter 27
27-2
CAUTION: We do not recommend using a skip block from any
fixed cycle block (such as drilling or turning). If you do choose
to execute a skip block in a fixed cycle mode, be aware that the
block that is skipped when the trigger occurs can be a cycle
generated block. If this is the case the cycle will continue
normal execution skipping only the portion of the cycle that was
executing when the trigger occurred. If the generated block
skipped is a crucial portion of the cycle, damage to the part or
machine tool can occur.
Use external skip functions to terminate the execution of motion
commands in a block when the control receives a signal through PAL.
When the program block is terminated any remaining axis motion
generated by the block that has not been performed remains unexecuted
(other non-motion commands are still performed). The control continues
normal program execution at the beginning of the next block following the
skipped block.
The external skip function is controlled by G31, G31.1, G31.2, G31.3, and
G31.4. The system installer determines what signal (such as a touch probe,
manual switch, etc.) corresponds to each G31 code in PAL. The system
installer can choose different signals to correspond to G31.2, G31.3, and
G31.4. G31 and G31.1 are functionally the same, always using the same
external signal and the same AMP defined feedrate. With proper PAL
programming, a G04 dwell in seconds may also be used as an external
skip function.
Format for any G31 external skip blocks is:
G31 X__ Z__ F__;
Where : Is :
G31 Any of the G-codes in the G31 series or G04. Use the one that is configured to
respond to the current external skip signal device that is being used.
X, Z The endpoint of the move if no external skip signal is received. These also
determine the direction that the tool travels in.
F The external skip function feedrate. If no value is entered here, the external skip
function executes at either the currently active feedrate, or the feedrate defined
for it in AMP (based on whether the AMP parameter Use AMP Skip Feedrate is
set to ”NO”or ”YES”). A value entered here replaces the currently active
feedrate and supersedes the AMP defined feedrate.
The G31 series of G-codes always produce linear motion regardless of the
current mode active at their execution. After their completion the control
returns to the operating mode active before the external skip block was
read (G00, G01, G02, G03).
27.1
External Skip
Functions (G31 codes)