Data Translation DT9820 Series, User Manual

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Chapter 2
20
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If wrap mode is single, data is written to a single buffer
continuously; when the buffer is filled, the module overwrites
the data in the buffer starting with the first location of the
buffer. This process continues indefinitely until you stop it.
Error Conditions
The DT9820 Series function modules can report an A/D overrun
error if the A/D sample clock rate is too fast. The error occurs if a new
A/D sample clock pulse occurs while the ADC is busy performing a
conversion from the previous A/D sample clock pulse. The host
computer can clear this error. To avoid this error, use a slower
sampling rate.
Note: The LED on the front panel will not blink green if the
hardware detects an error.
Synchronizing A/D Subsystems
You synchronize the operation of the A/D subsystems in two ways:
by synchronizing the triggers and by synchronizing the clocks. This
section describes these two methods.
Synchronizing the Triggers
You can synchronize the triggers of the A/D subsystems as follows:
• Software trigger
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Using software, specify the trigger source for
the A/D subsystems as the software trigger. Then, using
software, allocate a start list, put the A/D subsystems on the start
list, prestart the subsystems, and start the subsystems. When
started, the subsystems are triggered simultaneously.