The document describes a ladder logic program for controlling a traffic light system. The system has two switches: one to run the system according to one of two modes (normal or flashing), and another to select the mode. In normal mode, lights are green for 5 seconds and red for 5 seconds, with 1 second for yellow. In flashing mode, lights flash on and off independently. The ladder logic program uses timers, switches, and coils to control the lights according to the two modes.

1. 3- Traffic Light Control
Design a ladder program to solve the following control problem:
For the shown traffic light control system, there are two switches; the first one is to
run the system according the mode or leave it blank. There are two modes of
operation; Normal and Flashing. The time for green and red lights is 5 seconds, while it
is 1 second for the yellow lights, respectively. For simplicity assume one direction
streets.
Operation State Switch
Blank 0
MAIN
Run According to MODE 1
Normal 1
MODE
Flashing 0

2. Ladder STL
A "Main"
A "Mode"
CC "Normal"

3. A "Main"
AN "Mode"
CC "Flashing"
AN "Main"
CC "Blank"
FC1 AN T 4
L S5T#5S
SE T 3
NOP 0
NOP 0
NOP 0
A T 3
= L 0.0
A L 0.0
BLD 102
= "Red1"
A L 0.0
NOT
= "Green1"
A L 0.0
NOT
= "Red2"
A L 0.0
BLD 102
= "Green2"

4. AN T 3
L S5T#5S
SE T 4
NOP 0
NOP 0
NOP 0
NOP 0
A "Green1"
L S5T#4S
SE T 5
NOP 0
NOP 0
NOP 0
NOP 0
AN T 5
A "Green1"
= "Yellow1"

5. A "Green2"
L S5T#4S
SE T 6
NOP 0
NOP 0
NOP 0
NOP 0
AN T 6
A "Green2"
= "Yellow2"
FC2
AN "Mode"
R "Red1"
R "Green1"
R "Red2"
R "Green2"

6. AN T 2
L S5T#1S
SE T 1
NOP 0
NOP 0
NOP 0
A T 1
= "Yellow1"
= "Yellow2"
AN T 1
L S5T#1S
SE T 2
NOP 0
NOP 0
NOP 0
NOP 0
FC3
AN "Main"
R "Red1"
R "Yellow1"
R "Green1"
R "Red2"
R "Yellow2"
R "Green2"