7.6.6 Sequencers (Drum Programmers)
The MICRO 84 Programmable Controller can be used to produce a drum
type programmer on a circumferential row-by-row (sequencer) basis. Each
circumferential row can operate independently or dependently with
reference to the surrounding rows. The controller can contain up to eight
sequencers with up to sixteen contacts for each. Reference numbers for
sequencer contacts start with the digit 2 and are in the form 2RXX. The
significance of the remaining three digits of a sequencer contact reference
number is as follows:
Sequencers are controlled by the value (00-16) that is contained in a
sequence register (reference numbers 4001-4008).
Sequencer Register Reference Number:
4OOY
Sequencer Contact Reference Number:
2RXX
where:
R=
1 thru 8 (Sequencer reference register number 4001-4008)
xx = 01 thru 16 (Sequencer contact number)
Sequencer operation is controlled by a numeric value (1 thru 16) placed in
a specific sequencer register (4001-4008) by any of the non-relay devices
such as a counter, timer, or arithmetic operation. The value placed in the
sequencer reference register results in a single sequencer contact (2RXX)
being energized (contact closes). All other contacts are de-energized. As an
example, refer to Figure 7-7.
2300
2311
0
II
Figure 7-7. Sequencer Example
Each time input “count” contact (1001) is closed, the value in register 4003
increases by one. This is equivalent to moving the stepping switch one
position (clockwise). If register 4003 contains the value five, sequencer
contact 2305 is energized. When input 1002 is energized, the counter is
reset to zero and the stepping switch goes to home position (no contacts
closed).
Each sequencer is completely independent since each is controlled by a
separate register (4001-4008). Each sequencer contact reference number
(2RXX) can be used one or more times anywhere in the logic where a
contact is appropriate.
By using various logic techniques, any sequencer can be made to skip
steps and to jump forward or backward as necessary. Only one sequencer
contact (per sequencer) is in effect at any one time (i.e., contact points
between the jump points are not affected by the jump). The keystrokes
required to program a typical sequence are given in Appendix B.
7-10
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