Standard
RLL Instructions
5–30
Standard RLL Instructions
Timer, Counter, and Shift Register Instructions
Timer, Counter and Shift Register Instructions
Timers are used to time an event for a desired length of time. The single input timer
will time as long as the input is on. When the input changes from on to off the timer
current value is reset to 0. There is a tenth of a second and a hundredth of a second
timer available with a maximum time of 999.9 and 99.99 seconds respectively. There
is a discrete bit associated with each timer to indicate that the current value is equal
to or greater than the preset value. The timing diagram below shows the relationship
between the timer input, associated discrete bit, current value, and timer preset.
TMR T1
K30
X1
X1
T1
123456780
01020304050600
Current
Value
Timer preset
T1 Y0
OUT
Seconds
1/10 Seconds
There are those applications that need an accumulating timer, meaning it has the
ability to time, stop, and then resume from where it previously stopped. The
accumulating timer works similarly to the regular timer, but two inputs are required.
The start/stop input starts and stops the timer. When the timer stops, the elapsed
time is maintained. When the timer starts again, the timing continues from the
elapsed time. When the reset input is turned on, the elapsed time is cleared and the
timer will start at 0 when it is restarted. There is a tenth of a second and a hundredth
of a second timer available with a maximum time of 9999999.9 and 999999.99
seconds respectively. The timing diagram below shows the relationship between the
timer input, timer reset, associated discrete bit, current value, and timer preset.
X1
X1
T0
123456780
01010203040500
Current
Value
TMRA T0
K30
X2
X2
Reset Input
Start/Stop
Seconds
1/10 Seconds
Using Timers
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