Basic PLC Ladder Programming Examples 9

Basic PLC
Ladder Programming Training Examples for Beginners.

friends here we are starting here a series of Free Training on PLC
Ladder Programming training & tutorials.These PLC Ladder Programs
are important to get basics of Ladder programs.

Ladder Practice Problem: 

3 Motors Sequentially with delay i.e.
starting the oil pump motor immediately
when START is pressed. The main motor will be started after a 10 sec delay and
then the auxiliary motor after a 5 sec delay. In addition, stopping all motors
immediately when STOP is pressed.

Timing Diagram:

Topics Covered in this example is PLC Timer (Starting 3 Motors
of PLC Inputs Required

X1 –
Start Switch.

      X2 – Stop Switch.

Number of PLC Outputs Required

Y0 – OIL Motor
Y1 – Main Motor
Y2 – Auxiliary Motor

Number of PLC Timer Required

T0 – 10 second Timer, 100 ms Time Base. (See K100 Preset Value for
T1 – 5 second Timer, 100 ms Time Base. (See K50 Preset Value for Timer)

 PLC Ladder Programming:


PLC Ladder Program Description: 

When START is pressed, the NO contact X0 will be activated, which makes
Y0 to be ON and latched. The oil pump motor will start the lube system. At the
same time, [TMR T0 K100] instruction will be executed. When T0 reaches its set
value of 10 sec, the NO contact T0 will be ON.   
When the NO contact T0 is ON, Y1 will be ON and latched, which starts
the main motor and stops timer T0. At the same time, [TMR T1 K50] is executed,
and the NO contact T1 will be ON when timer T1 reaches its set value. 
When the NO contact T1 is ON, Y2 will be ON and latched, which starts
the auxiliary motor and stops T1.   
When STOP is pressed, the NC contact X1 will be activated, which makes
Y0, Y1 and Y2 OFF. The oil pump motor, main motor and auxiliary motor will stop

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