JYTEK USB-61210, Руководство пользователя

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24 Operation & Calibration
command is executed. The software then polls the conversion status
and reads back the A/D data when it is available.
This method is indicated when there is a need to process A/D data in
real time or instant closed-loop control. In this mode, the timing of the
A/D conversion is fully controlled by the software.
Continuous Acquisition Mode
Continuous A/D Conversion Clock Source
When the onboard ADC receives a conversion clock signal, A/D con -
version is triggered. The USB-61210 conversion clock may originate
with the internal hardware timer or externally via CONV (external
A/D conversion clock) pin. While the conversion clock source can be
chosen by setting AI source configuration, if precision acquisition is
required, use of the internal hardware timer is recommended.
Sampling Rate Control with Internal Hardware Timer
This mode is recommended if a fixed and precise A/D sampling rate
is required.The period between conversions of individual channels
can be accurately programmed. ADC sampling rate is determined by:
Sampling Rate = 2M/ScanIntrv Where ScanIntrv is scan interval counter, value
can be 1, 2, 3, 4… 2
32
- 1
WARNING:
The A/D conversion rate is determined by the software timer and
may not be precise.
TIMEBASE
DATA
D1
Acquisition
In Progress
Trigger
Acquisition begins following this clock edge
D1
ScanIntrv = 1
D2 D3 D4 D5 D6 D7 D8 D9 D10
D2 D3 D4 D5 D6
D1
D2 D3 D4
ScanIntrv = 2
ScanIntrv = 3