Continuing from the previous four articles, this main content explains the Off-Delay Timer.

1. Overall working principle

When the input signal is I, the timer starts to output, and when the input signal changes from 1 to 0, the timer starts to clock according to the set value, and the timing time stops the output. Reset to stop output within any period of time.

What it looks like in ladder chart programming:

the Off-Delay Timer

In the above figure, the S end is the signal input terminal; The TV side is the preset value input side, which is the timing time you want to set, and IOS is set here; The R end is the reset end; Bl and BCD are output to display the current time value, the display value type is different, BI is a hexadecimal format without a time reference, and BCD is S5T# format.

2. PLC programming examples and timing diagram explanations

PLC programming example

In the above figure, 10.1 is the normally open contact of the start button, which is used  to control the signal interruption, and when it is pressed, it becomes normally open and  closed, and the timer output begins to have a signal output (as shown in Figure 3 below).  When the input changes from I to O: the timer starts to clock according to the set value, and  the timing time stops the output. After the 10.1 input signal is stopped, the Q-side continues  to output without stopping until the timing time reaches the Q-end to stop the output, as  shown in Figure 4 below. When the 10.1 reset button is pressed at any time, the timer output  will change to 0 at any time and the signal output will stop (as shown in Figure 5 below).  

The input signal starts output when it is 1

Input signal disconnects output continues (within set time)

Sto the out ut after resetting

Action timing diagram

The above is the corresponding timing schematic. In order to help friends deepen their  impression, here is also a small question for everyone to think about: When the start button  is released and the timer is halfway (5s), when the start button is pressed again and  released, does the timer start from the beginning (IOS) or from the half (5s)?  

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