Asked by Tanyushka Little on Apr 29, 2024
Verified
The off-delay timer (TOF) starts timing when the timer's:
A) ladder rung switches from false to true.
B) ladder rung switches from true to false.
C) accumulated value equals its preset value.
D) accumulated value is greater than its preset value.
Off-Delay Timer
An electromechanical relay with contacts that change state a predetermined time period after power is removed from its coil; on re-energization of the coil, the contacts return to their shelf state immediately; also, a programmable logic controller instruction that emulates the operation of the electromechanical off-delay relay.
Ladder Rung
A single line of logic in a ladder diagram that equates to a control circuit, usually comprised of inputs and outputs represented by symbols.
- Familiarize oneself with the principles of operation for on-delay (TON) and off-delay (TOF) timers.
- Pinpoint the conditions necessary for initiating various timers in PLC code.
Verified Answer
JB
Jaquaisha BroadhurstMay 05, 2024
Final Answer :
B
Explanation :
The off-delay timer (TOF) starts timing when the ladder rung switches from true to false. This means that the timer will begin counting down once the input signal has turned off, and will continue to do so until the preset time has elapsed.
Learning Objectives
- Familiarize oneself with the principles of operation for on-delay (TON) and off-delay (TOF) timers.
- Pinpoint the conditions necessary for initiating various timers in PLC code.