LabVIEW
Samples to read option in DAQ
You can't write "nothing" in that box. The value must be 1 or greater.
It is a bit confusing, because in Continuous Mode, it really isn't Samples to Read, it is a range of buffer sizes - which was described in the previous reply.
Check out the HELP >>> Buffer Size
How Is Buffer Size Determined?
Input Tasks
If your acquisition is finite (sample mode on the Timing function/VI set to Finite Samples), NI-DAQmx allocates a buffer equal in size to the value of the samples per channel attribute/property. For example, if you specify samples per channel of 1,000 samples and your application uses two channels, the buffer size would be 2,000 samples. Thus, the buffer is exactly big enough to hold all the samples you want to acquire.
If the acquisition is continuous (sample mode on the Timing function/VI set to Continuous Samples), NI-DAQmx allocates a buffer equal in size to the value of the samples per channel attribute/property, unless that value is less than the value listed in the following table. If the value of the samples per channel attribute/property is less than the value in the table, NI-DAQmx uses the value in the table.
| Sample Rate | Buffer Size |
|---|---|
| No rate specified | 10 kS |
| 0–100 S/s | 1 kS |
| 100–10,000 S/s | 10 kS |
| 10,000–1,000,000 S/s | 100 kS |
| >1,000,000 S/s | 1 MS |
 |
Note For performance reasons, the default buffer size for continuous acquisitions differs slightly when logging is enabled. |
You can override the default buffer size by calling the Input Buffer Config function/VI.
NI-DAQmx does not create a buffer when the sample mode on the Timing function/VI is set to hardware-timed single point.
|
Note Using very large buffers may result in diminished system performance due to excessive reading and writing between memory and the hard disk. Reducing the size of the buffer or adding more memory to the system can reduce the severity of these problems. |
