Event driven sequencer application example, Reference, Event driven sequencer ladder program – Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers User Manual

Page 369

Application Example Programs

E–19

Data Files

Address

Data

N7:0

0000

N7:1

0000

0100

N7:2

0000

0010

N7:3

0000

0001

Data Table

Address

Data

(Radix=Decimal)

N7:0

6000

1500

3000

Event Driven Sequencer Application Example

The following application example illustrates how the FD (found) bit on an SQC
instruction can be used to advance an SQO to the next step (position). This
application program is used when a specific order of events is required to occur
repeatedly. By using this combination, you can eliminate using the XIO, XIC, and
other instructions. For a detailed explanation of:

•

XIC, XIO, and RES instructions, see chapter 6.

•

SQO and SQC instructions, see chapter 11.

Event Driven Sequencer Ladder Program

Rung 2:0
Ensures that the SQO always resets to step (position) 1 each REM Run
mode entry. (This rung actually resets the control register’s position
and EN enable bit to 0. Due to this the following rung sees a false to
true transition and asserts step (position) 1 on the first scan.)

Eliminate this rung for retentive operation.
| S:1 R6:0 |
|––] [–––––––––––––––––––––––––––––––––––––––––––––––––––––––(RES)––––|
| 15 |
| |

Reference