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Part 2
Introduction to the NI-DSP Analysis VIs
NI-DSP SRM for LabVIEW for Windows
1-7
Part 2: Introduction to the NI-DSP Analysis VIs
error out of the Copy Mem(LV to DSP) VI is
connected to the error in of the DSP Free
Memory VI
connected to the error in of the DSP Free
Memory VI
error out of the DSP Add VI is
connected to the error in of the
Copy Mem(LV to DSP) VI
connected to the error in of the
Copy Mem(LV to DSP) VI
Figure 1-9. An Example of Using the error in/error out Cluster for Sequential VI Execution
For more information about the error in/error out cluster, refer to Chapter 2, Error Handler VIs, in the LabVIEW
Utility VI Reference Manual.
Utility VI Reference Manual.
Hints for Improving the Execution Speed on the DSP Board
Check each of the following things to maximize your DSP board performance:
•
Allocate as many of the DSP Handle Clusters as you can before you operate on the data. Keep all data on the
DSP board until you finish all of the processing. Reduce the number of data transfers between the DSP board
and the PC as much as possible. The functions that run on the DSP board are very fast, but transferring data
between the DSP board and the PC and memory allocation slows the total processing performance.
DSP board until you finish all of the processing. Reduce the number of data transfers between the DSP board
and the PC as much as possible. The functions that run on the DSP board are very fast, but transferring data
between the DSP board and the PC and memory allocation slows the total processing performance.
•
Use the error in/error out cluster for sequencing VI execution. Be sure all of your VIs run in the correct
sequence. Use the error in/error out cluster to propagate the errors. If an error occurs, you can tell where the
error happens. You can use the LabVIEW error handler VIs in the Utility option of the Functions menu to
obtain pop-up error messages. Refer to the LabVIEW Utility VI Reference Manual for more information about
these VIs.
sequence. Use the error in/error out cluster to propagate the errors. If an error occurs, you can tell where the
error happens. You can use the LabVIEW error handler VIs in the Utility option of the Functions menu to
obtain pop-up error messages. Refer to the LabVIEW Utility VI Reference Manual for more information about
these VIs.
•
Many analysis routines on the DSP board can be performed in place; that is, the input and output array can be
the same array. This is very important to remember when you are processing large amounts of data. Large
32-bit floating-point arrays consume a lot of memory. If the results you want do not require that you keep the
original array or an intermediate array of data, perform analysis operations in place whenever possible. For
example, use the same DSP Handle Cluster for the input and output data buffers in your diagram in LabVIEW.
This will save your DSP board memory.
the same array. This is very important to remember when you are processing large amounts of data. Large
32-bit floating-point arrays consume a lot of memory. If the results you want do not require that you keep the
original array or an intermediate array of data, perform analysis operations in place whenever possible. For
example, use the same DSP Handle Cluster for the input and output data buffers in your diagram in LabVIEW.
This will save your DSP board memory.
•
Several intermediate-level data acquisition VIs work with DSP Handle Clusters. These VIs can acquire data
and leave it on the board. You can use the NI-DSP Analysis VIs to operate on this data and then copy the
processed results back to the PC. In this way, you dramatically reduce the data transfer overhead between the
PC and the DSP board, and improve the overall performance. For more information about these data
acquisition VIs, refer to the LabVIEW Data Acquisition VI Reference Manual. An example that shows you how
to use a DSP Handle Cluster to acquire data and process this data on the DSP board can be found in the
and leave it on the board. You can use the NI-DSP Analysis VIs to operate on this data and then copy the
processed results back to the PC. In this way, you dramatically reduce the data transfer overhead between the
PC and the DSP board, and improve the overall performance. For more information about these data
acquisition VIs, refer to the LabVIEW Data Acquisition VI Reference Manual. An example that shows you how
to use a DSP Handle Cluster to acquire data and process this data on the DSP board can be found in the
DSP2200
subdirectory of the
EXAMPLES
subdirectory of your
LabVIEW
directory.