Page 280 - Programmable Logic Controllers, Fifth Edition - Mobile version

Outputs 0 L2
7 6 5 4 3 2 1 0
1
1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1
2
2 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 3
3 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 4
5
4 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0
Position 6
5 0 0 0 0 0 0 0 0 1 1 1 0 0 1 1 1
7
6 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 8 Output module
7 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 9 at position 1
10
8 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1
11
Indicates that output is energized Sequencer output file words
12
Matrix-style chart
13
14
15
Figure 12-13 Sequencer chart.

An example of a time-driven sequencer program
in which the time interval between sequencer steps is
always a constant set value is shown in Figure 12-17.
Ladder logic program Outputs The operation of the program can be summarized as
L2
T4:1/DN SQO follows:
SEQUENCER OUTPUT EN North/South • The preset time of timer T4:0 is set for 3 seconds.
File #N7:0 DN
Mask 00FFh O:2/0 • The settings of the output bits for each sequencer
Dest O:2 position are entered and stored in bit file #B3:0.
Control R6:0 O:2/1
Length 4 • The timer is started by the closing switch SW and
Position 0 3 seconds later the timer done bit is set to 1.
O:2/2 • As a result the timer done bit increments the
SQO SQO instruction to the next position and resets
SEQUENCER OUTPUT EN the timer.
File #N7:10 DN East/West
Mask 00FFh • The destination is O:2 and all 16 bits of this word
Dest T4:1.PRE O:2/4 are used for outputs.
Control R6:0
Length 4 • The mask is FFFF hexadecimal or 1111111111111111
Position 0 O:2/5 binary, which allows all 16 bits to pass through.
• As long as input SW is closed the program contin-
T4:1/DN TON O:2/6 ues operating with 3 seconds between sequencer
TIMER ON DELAY EN steps.
Timer T4:1
Time base 1.0 DN
Preset 25
Accumulated 0

Timing chart
N/S Red Green Yellow
E/W Green Yellow Red
25 s 5 s 25 s 5 s
Figure 12-15 Sequencer file #N7:0 light cycle settings.
Figure 12-14 Time-driven sequencer output program. Source: Courtesy of TheLearningPit

Sequencer and Shift Register Instructions Chapter 12 261

pet73842_ch12_252-280.indd 261 03/11/15 7:19 PM