Data Translation DT9828, Руководство пользователя

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Principles of Operation
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Input Trigger
The DT9828 modules support a software trigger event to start the analog input operation. A
software trigger occurs when you start the analog input operation (the computer issues a
write to the module to begin conversions). Using software, specify the trigger source as a
software trigger.
Analog Input Conversion Modes
DT9828 modules support single-value and continuous scan conversion modes. This section
describes each of these conversion modes.
Single-Value Operations
Single-value operations are simpler to use than continuous operations. Using software, you
specify the analog input channel that you want to use. For the DT9828, specify channel 0, 1, 2,
3, 4, 5, 6, or 7. The module acquires the data from the specified channel and returns the data
immediately.
For single-value operations, you cannot specify a clock frequency, trigger source, scan mode,
or buffer. Single-value operations stop automatically when finished; you cannot stop a
single-value operation.
Table 2: Example of Per Channel Sampling Frequency
Number of
Input
Channels
Total Throughput (Hz)
600 300 200 120 100 60 40 10 6 1
1 600.00 300.00 200.00 120.00 100.00 60.00 40.00 10.00 6.00 1.00
2 300.00 150.00 100.00 60.00 50.00 30.00 20.00 5.00 3.00 0.50
3 200.00 100.00 66.67 40.00 33.33 20.00 13.33 3.33 2.00 0.33
4 150.00 75.00 50.00 30.00 25.00 15.00 10.00 2.50 1.50 0.25
5 120.00 60.00 40.00 24.00 20.00 12.00 8.00 2.00 1.20 0.20
6 100.00 50.00 33.33 20.00 16.67 10.00 6.67 1.67 1.00 0.17
7 85.71 42.86 28.57 17.14 14.29 8.57 5.71 1.43 0.86 0.14
8 75.00 37.50 25.00 15.00 12.50 7.50 5.00 1.25 0.75 0.13