Timer

Operator Menu Location: Time

Operator Bitmap:
 

Functional Description:
The Timer operator measures elapsed time. It is activated when the Trigger (T) input is HIGH. After the Timer is activated, the output remains LOW until the time specified by the Delay (D) input (in seconds) elapses. After the Delay time elapses, the output will go HIGH, and remain HIGH until the Reset (R) input goes HIGH. After a Reset pulse is applied, the timer can be triggered again.
The state transition diagram shown below illustrates the functional behavior of the Timer operator. 

 
It consists of three states: a disarmed state with the output LOW---the initial state; (ii) an armed state with the output LOW; and (iii) a HIGH output state. The operator transitions from the disarmed state to the armed state when input T(t)=HIGH. The time instant when the Timer is armed or triggered is recorded as . Once armed, the Timer will begin to record the elapsed time. It will transition from the armed state to the HIGH output state when

The operator transitions to the disarmed state whenever input R(t) = HIGH.
The Timer operator can be configured to issue a pulse at regular intervals. For example, the simple schema shown in the figure below will produce a short pulse every hour.

The Timer operator can also be configured to function as a square-wave generator. For example, in the schema shown below, two Timer operators continually activate and deactivate a Relay Output operator in alternating 10 second periods. (The same result can be obtained with the PWM Signal operator.)

User-Defined Properties:
Object Name. A string label that identifies the operator

Enable On. Determines where in a signal the Timer becomes active

Display Reset Pin. This property determines if input pin R is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Display Trigger Pin. This property determines if input pin T is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Comments:
The Timer operator cannot measure events greater than 139.8 minutes (8,388 seconds). Therefore, input D may not exceed 8,388 when the timer is activated.

See Also:
PWM Signal, Square Wave Generator, Delay Element