Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 559)

Surface Grinding Fixed Cycles
Chapter 16
16-9
I - reciprocating axis distance, secondary reversal point.
If in incremental mode (G91 active) then the value entered here is a signed
incremental value used to indicate the distance from the start point to the
end of the secondary reciprocating motion. If in absolute mode (G90
active) then the value entered here is the X coordinate of the end point of
the secondary reciprocating motion. If no value is entered for this, then the
start point is used as the end point of the secondary reciprocating motion.
The start point for the reciprocating axis is the coordinate of the X axis
prior to execution of the surface grinding cycle. If the X axis is already
reciprocating when the surface grinding cycle block is executed, then the
start point (when incremental mode is active) is the secondary reversal
point. This was explained on page 16-4.
This parameter is “program modal,” meaning that it needs to be
programmed only once in a part program. Any subsequent surface
grinding blocks (G82 -- G86) use a previously programmed value if a new
value is not programmed. Programming an I word in any program block
while reciprocation is active changes the coordinate of the secondary
reversal point.
Important: In grinding fixed cycle blocks where changes are made from
absolute to incremental or incremental to absolute modes within the block,
the integrands I, J and K are always in the last mode programmed in the
block, regardless of their position in the block.
Important: It is the programmer’s responsibility to make sure that the
crossover and reciprocating moves extend beyond the part sufficiently such
that the plunge move can be completed before the wheel comes back in
contact with the part. Crossover and plunge moves begin as the
reciprocation axis decelerates. Therefore, feedrate, acceleration and
deceleration should be considered for all axes involved.
Z - crossover position.
If in incremental mode (G91 active) then the value entered here is a signed
incremental value used to indicate the distance from the start point to the
end of the crossover motion. If in absolute mode (G90 active) then the
value entered here is the Z coordinate of the end point of the crossover
move.
This parameter is “program modal,” meaning that it needs to be
programmed only once in a part program. Any subsequent surface
grinding blocks (G82 -- G86) use a previously programmed value if a new
value is not programmed.