Preface, Operation – Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers User Manual

Page 202

Preface

MicroLogix 1000 Programmable Controllers User Manual

11–14

Status bits of the control structure include:

–

Error Bit ER (bit 11) is set when the controller detects a negative
position value, or a negative or zero length value. When the ER bit is set,
the minor error bit (S5:2) is also set. Both bits must be cleared.

–

Done Bit DN (bit 13) is set after the instruction has operated on the last
word in the sequencer load file. It is reset on the next false-to-true rung
transition after the rung goes false.

–

Enable Bit EN (bit 15) is set on a false-to-true transition of the SQL rung
and reset on a true-to-false transition.

Operation

Instruction parameters have been programmed in the SQL instruction shown below.
Input word I:0.0 is the source. Data in this word is loaded into integer file #N7:30
by the sequencer load instruction.

(EN)

(DN)

SQL

SEQUENCER LOAD
File

#N7:30

Source

I:0.0

Control

R6:4

Length

Position

0000

0101

0000

1010

0000

1010

0010

1111

0101

0000

0101

0000

1010

0000

0
1
2
3
4

Step

N7:30

31
32
33
34

Word

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15

External Inputs
Associated with I:0.0

Source I:0.0

Sequencer Load File #N7:30

Current Step

When rung conditions change from false-to-true, the SQL enable bit (EN) is set.
The control element R6:4 increments to the next position in the sequencer file, and
loads the contents of source I:0.0 into the corresponding location in the file. The
SQL instruction continues to load the current data into this location each scan that
the rung remains true. When the rung goes false, the enable bit (EN) is reset.