Keithley DAS-1700 Series
Using the DAS-1700 Series with DriverLINX
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43
Rate Generator: External Clocking
An externally clocked Rate Generator produces a rate clock with unknown time
intervals between tics.
Period (ext clk)
Use an externally clocked rate generator when you want to synchronize analog input
samples with a recurrent external signal. In this mode you will need a separate
external clock tic for each analog sample you want to acquire.
How to set up the DAS-1700 Series for fixed rate sampling using an external clock.
Be sure that the external
clock source is TTL
compatible, 0 V minimum to
+5 V maximum!
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Specify external clocking using a
Rate
Generator on Channel
0
with
an
External, E
, or
External-
Clock source. See
“Counter/Timer Subsystem” on page 101 for a description of clock
sources. For hardware-independence, you can specify the hardware
external clock channel by the symbolic constant, DI_EXTCLK.
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Users should connect the external clock signal to the XPCLK line.
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Specify a Period between the minimum and maximum external
clocking period. The value doesn’t affect the external clock frequency,
but DriverLINX requires a valid hardware value in case the application
requests a timebase operation and to optimize data transfer between the
driver and the application.
•
The frequency of the external clock must not exceed 162.5 kHz (50
kHz for HR models).
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