GE PACSystems RX7i

Chapter 4. Ladder Diagram (LD) Programming
GFK-2950C February 2018 231
Timer On Delay
When the input IN transitions from OFF to ON, the timer starts timing until a
specified period of time (PT) has elapsed, then sets the output Q to ON.
Timing Diagram
t0
t1
t2
t4
IN
Q
ET
t3
PT
PT
t0
When input IN is set to ON, the timer starts to measure time and the elapsed time output ET
starts to increment. The output Q remains OFF and ET continues to increment until its value
equals the preset time, PT.
t1
When ET equals PT, the output Q is goes ON, and ET remains at the preset time, PT. Q remains
ON until IN goes OFF.
t2
When IN is set to OFF, Q goes OFF and ET is set to 0.
t3
When IN is set to ON, ET starts To increment.
t4
If IN is ON for a shorter time than the delay specified in PT, the output Q remains OFF. ET is set
to 0 when IN is set to OFF.
Example
In the following sample rung, a TON function block is used to delay setting Start to ON for 1 minute
(60,000ms) after Preheat is set to ON.