This is PLC Program for controlling conveyors ON sequence and OFF sequence.
Problem
Description:-
There are three belt conveyor in the system. We need
to control sequences of conveyors both ON sequence and OFF sequence. Implement
logic in PLC using ladder diagram programming language.
Problem
Diagram
Problem
Solution.
We will use PLC S7-300
for this application. Also we will use TIA portal software for programming.
Conveyor belt 1 or conveyor belt 2 can be started by the corresponding START
pushbuttons and can be stopped by corresponding STOP push buttons.
Conveyor
belt 3 should always transport when either conveyor belt 1or conveyor belt 2 is
transporting.
When OFF pushbutton is pressed, belt 1 or belt 2 is to
continue running for 20 sec. and belt 3 for 60 seconds to clear the belts of
material and Then stopped.
There is 10 Hz. monitoring signal for belt status
monitoring for all three belts. If there is fault in any one of the belts then
the entire belt should turn off immediately.
And OFF indications of previously running
belts should flash with 5 HZ frequency.
Program
Here
is PLC program for controlling
conveyors ON sequence and OFF sequence.
List
of inputs/outputs
List
of inputs
System ON/OFF switch:-I2.0
Belt 1 START:-I0.0
Belt 1 STOP:-I0.1
Belt 2 START:-I0.2
Belt 2 STOP:-I0.3
Belt 1 fault:-I1.0
Belt 2 fault:-1.1
Belt 3 fault:-I1.2
List
of outputs
Conveyor belt 1:-Q0.0
Conveyor belt 2:- Q0.1
Conveyor belt 3:-Q0.2
Belts running indication:-Q0.3
Fault indication:-Q0.4
Fan 3 ON Indication:-
Q0.6
Main supply ON
indication:-Q0.7
M
memory:-
Cycle ON:-M0.0
5HZ clock pulse:-M0.5
10HZ clock pulse:-M1.0
Ladder
diagram for controlling
conveyors ON sequence and OFF sequence.
Program Description
For this application we
used S7-300 PLC and TIA portal software for programming.
Network
1:-When
system ON switch (I2.0) is pressed, cycle ON (M0.0) bit will be ON.
Network
2:-When
belt 1 START PB (I0.0) is pressed, Conveyor belt 1(Q0.0) will be ON.
Network
3:- When
conveyor belt 1 STOP button (I0.1) is pressed, timer will start to count time
and after 20s timer will stop the conveyor belt 1 (Q0.0). If fault occur in
conveyor belt 1, belt 1 should be STOP.
Network
4:-When
belt 2 START PB (I0.2) is pressed, conveyor belt 2 (Q0.1) will be ON.
Network
5:- When
conveyor belt 2 STOP button (I0.3) is pressed, timer will start to count time
and after 20s timer will stop the conveyor belt 2 (Q0.1). If fault occur in
conveyor belt 2, belt 2 should be STOP.
Network
6:-Either
conveyor belt 1 (Q0.0) or conveyor belt 2 (Q0.1) is ON, Conveyor belt 3 (Q0.2)
will be ON. If fault occur in conveyor belt 3, it should be STOP.
Network
6:-When
both conveyors are OFF, Conveyor 3 off timer will be executed.
Network
7:-When
conveyor belt 3 timer is executed, after 30s it will stop the conveyor belt 3
(Q0.2).
Network
8:-Either
conveyor belt 1 STOP PB (I0.1) or conveyor belt 2 STOP PB (I0.3) is pressed,
conveyor 1&2 reset timer will be executed.
Network
9:-If
three conveyors are running in healthy condition, belts running indication lamp
(Q0.3) blinks on 10HZ frequency.
Network
10:-If
any conveyor belt is faulty out of three belts, fault indication lamp (Q0.7)
will start to blink on 5HZ frequency.
Note:-Above
application may be different from actual application. This example is only for
explanation purpose only. We can implement this logic in other PLC also. This
is the simple concept of conveyor ON and conveyor OFF sequence in industry, we
can use this concept in other examples also.
All
parameters considered in example are for explanation purpose only, parameters
may be different in actual applications. Also all interlocks are not considered
in the application.
Runtime
Test Cases
|
Inputs |
Outputs |
Physical Elements |
|
I2.0=1 |
M0.0=1,Q0.7=1 |
Cycle ON, main supply On indication lamp ON |
|
I0.0=1 |
Q0.0=1 |
Conveyor belt 1 ON |
|
I0.2=1 |
Q0.1=1 |
Conveyor belt 2 ON |
|
Q0.0=1or Q0.1=1 |
Q0.2=1 |
Conveyor belt 3 ON |
|
I1.0=1orI1.1=1orI1.2=1 |
Q0.4=1 |
Fault indication lamp ON |