Measurement Computing ADAC-LVi - Manual (Page 31)

Chapter 2 Intermediate Analog Input VIs
ADAC LabVIEW VI 25
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Clock Source (SwConvert:0) Clock Source is a numeric value that sets the hardware
clocking source. The available options are:
0:SOFTWARE_CONVERT Software clocked acquisition, supported by all A/D's.
1:INTERNAL On-board clocking acquisition, supported by A/D's with DMA, Interrupt
or FIFO capabilities.
2:EXT_RISING_EDGE External clocking rising edge, supported by A/D's with DMA,
Interrupt or FIFO capabilities.
3:EXT_FALLING_EDGE External clocking falling edge, supported by A/D's with
DMA, Interrupt or FIFO capabilities.
4:MMTIMER Multi-Media system timer, supported by the 4012AD and 4112AD series
in the Windows 95/98 environment only.
The default Clock Source is 0:SOFTWARE_CONVERT
Clock Rate Units (Hertz:0) Units is a numeric value that specifies base units in which
the Clock Rate parameter is specified. The available options are:
0:HERTZ Rate is specified in units of hertz (samples per second)
1:TICS Rate is the divisor programmed to the on-board clocking source.
2:MSECONDS Miliseconds, supported by the 4012AD and 4112AD series in the
Windows 95/98 environment only. The 4012 or 4112 series can be set to either HERTZ
or MSECONDS only.
If TICS is chosen, the Clock Rate parameter is used to specify the divisor to the on-
board CLK input source. The on-board clock source is typically an 8254 device that has a
1,000,000 CLK input source. The 1,000,000 source is divided from 2 to 65525 to set
actual A/D clocking rate.
For boards that use 2 on-board clocks concatenated together, the divisor broken into two
16bit WORDS. The high word divides the first CLK that feeds the second CLK that is
further divided by the low word.
The default Unit is 0:HERTZ