# Ladder Logic Timer On Delay Instruction

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## TON - Timer On-Delay

• Count time base intervals when the instruction is true.
• The Timer On Delay instruction begins to count time base intervals when rung conditions become true. As long as rung conditions remain true, the timer adjust its accumulated value (ACC) each evaluation until it reaches the preset value (PRE).
• The accumulated value is reset when rung conditions go false, regardless of whether the timer has timed out or not.

#### Example 1

Lets say that we have a conveyor, siren and 1 limit switch LS-01. LS-01 is at the beginning of the conveyor. When LS-01 is ON we want a buzzer to go on for 3 seconds (Security) and then we want to start the conveyor. When LS-01 is cleared then we want to stop the conveyor.

#### Input / Output

• Conveyor O:2.0/0
• Siren O:2.0/1
• LS-01 I:1.0/0

#### Ladder Logic Solution

Once LS-01 goes on then the timer will start timing. Note that the time base is set to 1.0(second), and preset is 3 therefore total times is set to 3 seconds.

Since LS-01 is on and accumulated value of the time is not reached yet this will energize the siren. This rung will be kept energized till the 3 seconds are passed.

Once the Accumulated value gets equal to the preset value (3 seconds) the Done value will be on and hence the conveyor will start, it will stop when LS-01 goes off.

#### Note

• When the timer is energized the timer will start timing till its accumulation value is equal to preset value. If during this time the timer is de-energized then the timer will reset it and set the Acc value to zero.
• Watch the use of the TON done. (T4: 0.DN)
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