NuDAQ PET-48DIO, Руководство пользователя, Страница: 19 / 38

Installation
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2.9.3 Timer Clock Source Setting JP12
The JP12 is for select timer clock source. The range of timer is
depend on clock source, PET-48DIO has two clock sources for timer,
and setting range shows as table.
Clock source Timer setting range
32.768 KHZ 0.000122 sec ~ 131072 sec
2 MHZ 0.000002 sec ~ 2147.4836 sec
The following equation is to calculate ti mer setting range.
Timer range = 1 / (Timer Clock source / (Divide 1* Divide 2))
Divide 1 is loading data of 8253 counter 1.
Divide 2 is loading data of 8253 counter 2.
For example:
Clock source is 32.768 KHZ. Set timer to 0.0122 Sec.
0.0122=1/(32768/(Divide 1*Divide 2))
(Divide 1*Divide 2)=400
Let Divide 1=2-> Hex0002 So Divide 2=200 -> Hex 00C8
Select 32.768KHz
Select 2 MHz
(Default setting)