Table of Contents
Advertisement
Chapter 5
When it detects a software trigger, the host computer transfers the entire waveform pattern to
the 8 kByte output FIFO on the module, and the module starts writing output values to the
analog output channel at the specified clock rate. The module recycles the data, allowing you
to output the same pattern continuously without any further CPU or USB bus activity.
When it reaches the end of the FIFO, the module returns to the first location of the FIFO and
continues outputting the data. This process continues indefinitely until you stop it.
To select waveform generation mode, use software to specify the following parameters:
• Specify the data flow as Continuous
• Specify WrapSingleBuffer as True to use a single buffer
• Specify the clock source as internal and specify the clock frequency. Refer to
• Specify a software trigger source, described in the next section
Note: On the DT9837, an error will be reported if you specify a buffer with greater than 8192
samples (the size of the output FIFO on the module).
If you want to output data from the analog output channel on the DT9837 module while
acquiring analog input data, ensure that you set up and start the analog output operation
before starting the analog input operation, or an error will be reported.
The DT9837, DT9837A, and DT9837C modules support the ability to mute the output voltage
to 0 V. Muting the output does not stop the analog output operation; instead, the analog
output voltage is reduced to 0 V over 1020 samples. When desired, you can unmute the output
voltage to its current level. Refer to your software documentation for more information on
muting and unmuting the output voltage.
Continuous Analog Output Operations
Continuous analog output operations are supported on the DT9837A module only. Use
continuously paced analog output mode to continuously output buffered values to the analog
output channel at a specified clock frequency. The DT9837A and DT9837C support the ability
to start continuous analog output operations and continuous analog input operations
simultaneously.
Use software to fill multiple output buffers with the values that you want to write to the
analog output channel. When it detects the specified trigger, the module starts writing the
values from the output buffer to the analog output channel at the specified clock frequency.
The operation repeats continuously until either all the data is output from the buffers or you
stop the operation.
Note: Make sure that the host computer transfers data to the output channel list fast enough
so that the list does not empty completely; otherwise, an underrun error results.
78
more information about the clock source and frequency.
page 76
for
Advertisement
Table of Contents
