Basic PLC Ladder Programming Example 15


Basic PLC
Ladder Programming Training Example 15 : Automatic Door Open Close System PLC Ladder
Program 

Basic PLC Ladder Programming Training Examples for Beginners. Hi
Friends here we are starting a series of Free Training on PLC Ladder
Programming. These PLC Ladder Programs are important to get basics of Ladder
Programs

PLC Ladder
Practice Problem:



  • When someone enters the infrared sensing field, opening motor
    starts working to open the door automatically till the door touches the opening
    limit switch 
  • If the door touches the opening limit switch for 7 sec and nobody
    enters the sensing field, the closing motor starts working to close the door
    automatically till the closing limit switch touched together.
  • Stop the closing action immediately if someone enters the sensing
    field during the door closing process.
Topics
Covered in this example is Automatic
opening closing Door PLC Program  
Number of
PLC Inputs Required 

X0 – X0 = ON when someone enters the sensing
field.
X1 – Closing limit switch. X1 = ON when 2
switches touched together.
X2 – Opening limit switch. X2 = ON when the
door touched the switches. 
Number of
PLC Outputs Required 

Y0 -Opening motor
Y1 – Closing motor  
Number of
PLC Timers Required 

T0 – 7 sec timer. Time base: 100ms 
Number of
PLC internal memory flag Required

M1013 – 1s clock 

PLC Ladder
Programming: 


PLC Ladder Program for Automatic Door open Close

PLC Ladder
Programming Description: 

  •  X0 = ON if someone enters the sensing field of the infrared
    sensor. Y0 will be ON and latched, and the door will be opened as long as the
    opening limit switches X2 = OFF. 
  • When the door touches the opening limit switches, X2 = ON. The
    timer T0 will start to count for 7 sec if no one enters the sensing field (X0 =
    OFF). After 7 sec., Y1 will be ON and latched and the door will be closed.
  • During the closing process, X0 = ON if someone enters the sensing
    field. The NC contact X0 will be activated to turn Y1 off. Because X0 = ON, X2
    = OFF and Y1 = OFF, Y0 will be ON and the door will be opened once again. 









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