Preface
MicroLogix 1000 Programmable Controllers User Manual
12–32
The high-speed counter is used to control the conveyer position. The high-speed
counter counts pulses supplied by the conveyer’s encoder via hardware inputs I:0/0
and I:0/1. Hardware inputs I:0/2 (reset) and I:0/3 (hold) are connected to a
photo-switch ensuring the HSC instruction only counts encoder pulses when a
manual is in front of the drill and that the high-speed counter is reset at the leading
edge of each manual.
The high-speed counter clears the conveyer drive output bit (O:0/0) each time a high
preset is reached. As a result, the drive decelerates and stops the conveyer motor.
The high-speed counter clears the output within microseconds ensuring accuracy
and repeatability.
The high-speed counter sets the conveyer drive output bit (O:0/0) each time a low
preset is reached. As a result, the drive accelerates and maintains the conveyer
motor.
When the manual has travelled the specified distance set by the high-speed counter
high preset value, the high-speed counter interrupt subroutine signals the main
program to perform the drilling sequence. For more information regarding the
interrupt subroutine used in this program, refer to the application example in
chapter 11.
This example uses the Quadrature Encoder with reset and hold instruction. The
high-speed counter accumulator increments and decrements based on the quadrature
relationship of the encoder’s A and B inputs (I:0/0 and I:0/1). The accumulator is
cleared to zero when the reset is activated or when the RES instruction is executed.
All presets are entered as a relative offset to the leading edge of a manual. The
presets for the hole patterns are stored in the SQO instructions. (Refer to chapter 11
for the SQO instruction.) The high-speed counter external reset input (I:0/2) and the
external hold input (I:0/3) are wired in parallel to prevent the high-speed counter
from counting while the reset is active.
The input filter delays for both the high-speed counter A and B inputs (I:0/0 and
I:0/1) as well as the high-speed counter reset and hold inputs (I:0/2 and I:0/3) can be
adjusted. Refer to page A–7 for more information on adjusting filters.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
