# Ladder Logic Example with Timers

Build the ladder logic example with Timers to turn ON/OFF the lamp using push buttons with respect to program logic conditions.

### PLC Logic

#### 2. After Start PB is pressed,

• In the following sequence Outputs should turn ON/OFF
• Q1 is turn ON for 5 sec
• Q2 is turn ON for 5 sec
• Q3 is turn ON for 5 sec
• Q4 is turn ON for 5 sec

#### 3. End of above sequence will trigger,

• All four outputs (Q5, Q6, Q7, Q8) to turn ON.
• In the following sequence, outputs should turn OFF after its turned ON,
• After 5 sec, Q5 should go OFF
• After 5 sec, Q6 should go OFF
• After 5 sec, Q7 should go OFF
• After 5 sec, Q8 should go OFF

Note: Process should continue until stop PB is pressed

## Ladder Logic Example with Timers

### Logic Description

#### RUNG 0000

Latching rung to operate the system through Master Start and Stop PB.

#### RUNG 0001

Latched B3:0/0 is connected with T4:0 which starts running. Normally closed contact of T4:1 timer done bit is connected to make the process continue until stop PB is pressed.

#### RUNG 0002

Greater than or equal and Less than or equal block is connected in series with Q1 (O:0/0),When accumulator value between 0 to 5  triggers Q1 turns ON.

#### RUNG 0003

Greater than or equal and Less than or equal block is connected in series with Q2 (O:0/1),When accumulator value between 6 to 10  triggers Q2 turns ON.

#### Rung 0004

Greater than or equal and Less than or equal block is connected in series with Q3 (O:0/2),When accumulator value between 11 to 15  triggers Q3 turns ON.

#### Rung 0005

Greater than or equal and Less than or equal block is connected in series with Q4 (O:0/3),When accumulator value between 16 to 20  triggers Q4 turns ON.

#### Rung 0006

When T4:0 accumulator value reaches 20,outputs Q5.Q6,Q7 & Q8 turns ON along with timer T4:1 which presets for 20 second. Limit block is used turn OFF each output in respective sequence.

Each Limit block check with T4:1’s accumulator value, when it’s not in the limit its triggers the output to turn OFF.

### Conclusion:

The above explained ladder logic for lamp turn ON/OFF is for example only. We can use this example program to understand the working of Push Buttons, Timers and Limit block in Allen Bradley PLC.

Author : Hema Sundaresan

One Shot Rising PLC Logic