What Is TIMERS In PLCs & Types - SKengineers

 

TIMERS

DEFINITION : A timer is a special counter ladder function that allows the PLCs to perform timing operations based on a precise internal clock.

TYPES OF TIMERS :

1.      Delay ON timers or ON delay timers

2.      Delay OFF timers or OFF delay timers

3.      Pulse timers

4.      Cascaded timers

5.      ON-OFF cycle timers

6.      One shot timers

1)     DELAY ‘ON’ TIMERS :

·        The term delay is used to indicate that this timer burns on, after waiting for a fixed time delay period.

·        When there is an input, the timer is energized and start timing, after some pre-set value, the timer contacts are closed to outputs.

·        TON is used to denote ON- delay.

2)     DELAY OFF TIMERS :

·        OFF delay timers are maintained as ON for a fixed time of delay period before turning off.

·        TOF is used to denote OFF-delay.

3)     PULSE TIMERS :

·        Pulse timer switches is another type of timer which comes either ON or OFF for a fixed period of time as a function of pulses.

·        TP is used to denote pulse timers.

4)     CASCADED TIMERS :

·        Cascading means more elements are linked together to form a system.

·        The cascading timers are linked together to give longer delay times which is easily achieved than just one timer.

5)     ON-OFF CYCLE TIMER :

·        Timers producing an output for some period and no output for some period and an output for some period.

·        The timer is designed to switch on output for T sec and off for another T second.

6)     ONE SHOT TIMERS :

·        One shot timer produces an output for a fixed length of some initiation input.