Short description

The output with off-delay is not reset until a defined time has expired.

Connection	Description
Input Trg	Start the off-delay time with a negative edge (1 to 0 transition) at input Trg (Trigger).
Input R	Reset the off-delay time and set the output to 0 via the R (Reset) input. Reset has priority over Trg.
Parameter	T: The output is switched off on expiration of the delay time T (output signal transition 1 to 0). Retentivity on = the status is retentive in memory.
Output Q	Q is switched on for the duration of the time T after a trigger at input Trg.

Parameter T

The time set in parameter T can be provided by the actual value of another already-programmed function:

• Analog comparator: Ax - Ay

• Analog threshold trigger: Ax

• Analog amplifier: Ax

• Analog multiplexer: AQ

• Analog ramp: AQ

• Mathematic instruction: AQ

• PI controller: AQ

• Up/Down counter: Cnt

For the 0BA7 devices, you can additionally use the actual values of the following already-programmed functions:

• On-delay: Ta

• Off-delay: Ta

• On-/off-delay: Ta

• Retentive on-delay: Ta

• Wiping relay(pulse output): Ta

• Edge triggered wiping relay: Ta

• Asynchronous pulse generator: Ta

• Stairway light switch: Ta

• Multiple function switch: Ta

• Stopwatch: AQ

• Analog filter: AQ

• Average value: AQ

• Max/Min: AQ

• Thresholder trigger: Fre

You select the required function by the block number.

For information on the validity and accuracy of the time base, refer to the LOGO! manual.

Timing diagram

Description of the function

Output Q is set to 1 instantaneously with a 0 to 1 transition at input Trg.

At the 1 to 0 transition at input Trg, LOGO! retriggers the current time T, and the output remains set. The output Q is reset to 0 when T_a reaches the value specified in T (T_a=T) (off delay).

A one-shot at input Trg retriggers the time Ta.

You can reset the time Ta and the output via the input R (Reset) before the time Ta has expired.

Special Functions Overview