FANUC PMC-MODEL SD7
EDIT DATE DESIG.
The 1st level sequence part operates every 8 ms (high-speed sequential
If the 1st level sequence part is long, the total operating time, including the
2nd level sequence part, is extended. Therefore the 1st level sequence part
must be programmed to be processed in as short time as possible.
The 2nd level sequence part operates every 8×n ms. Here n is a dividing
number for the 2nd level sequence part.
The 2nd level sequence part is divided automatically when the sequence
program is executed. The time for one cycle of the sequence program is
displayed on the TITLE screen.
(1) Division of the 2nd level sequence part
The 2nd level sequence part must be divided in order to execute the 1st
level sequence part. For example a sequence program is executed in the
following sequence when the dividing number is n. (See Fig. 2.1)
After the last division of 2nd level sequence part (division n) is executed,
the sequence program is executed again from the beginning. Thus, when
the dividing number is n, the cycle of execution is 8msec×n.
The 1st level sequence operates every 8msec, and the 2nd level sequence
every 8×n msec. If the steps of the 1st level sequence is increased, the
steps of the 2nd level sequence operating within 8msec becomes less,
thereby increasing the dividing number and making the processing time
longer. Therefore, it is desirable to program so as to reduce the 1st level
sequence to a minimum.
In the PMC-SD7, 7msec of 8msec is assigned to execution of the 1st and
2nd level sequences.
(2) 1st level sequence part
Only short-width pulse signals are processed. These signals include
emergency stop, over-travel of each axis, reference point return
8ms 8ms 8ms
7ms 7ms 7ms
Fig. 2.1 About priority of execution.