Data Translation DT9834 Series, Руководство пользователя

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Chapter 5
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Data Format and Transfer
Data from the host computer must use offset binary data encoding for analog output signals,
such as 000 (for 12-bit modules) or 0000 (for 16-bit modules) to represent
−
10 V, and FFFh (for
12-bit modules) or FFFFh (for 16-bit modules) to rep10 V. Using software, specify the
data encoding as binary.
Before you begin writing data to the output channels, you must allocate and fill buffers with
the appropriate data. An event is generated whenever a buffer is output. This allows you to
output additional data as needed.
Error Conditions
The DT9834 Series modules can report an error if one of the following conditions occurs:
• Output FIFO Underflow – The output channel list data is not being sent from the host fast
enough. This error is reported if an output sample clock pulse occurs while the output
channel list is empty. Note that if no new data is available to be output by either the DACs
or the digital output port, the last value placed in the output channel list continues to be
output by the DACs/port. You can ignore this error when performing a single-value
operation.
• DAC Over Sample error – The output sample clock rate is too fast. This error is reported
if a new output sample clock occurs while the module is busy loading the next values
from the output channel list into the DACs and/or digital output port. To avoid this error,
try slowing down the D/A clock, using a different wrap mode, increasing the buffer sizes,
or using more buffers.