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PicoScope 4000 Series (A API) Programmer's Guide 15

3.6.3

Streaming mode

Streaming mode can capture data without the gaps that occur between blocks when

using block mode. It can transfer data to the PC at speeds of up to 160 MS/s,

depending on the computer's performance. This makes it suitable for high-speed

data acquisition, allowing you to capture long data sets limited only by the

computer's memory.

Downsampling. The driver returns downsampled readings while the device is

streaming. If the downsampling ratio is set to 1, only one buffer is returned per

channel. When the downsampling ratio is greater than 1 and aggregation mode is

selected, two buffers (maximum and minimum) per channel are returned.

Memory segmentation. The memory can be divided into segments to reduce the

latency of data transfers to the PC. However, this increases the risk of losing data if

the PC cannot keep up with the device's sampling rate.

See Using streaming mode for programming details.

3.6.3.1

Using streaming mode

This is the general procedure for reading and displaying data in streaming mode using

a single memory segment:

1. Open the oscilloscope using ps4000aOpenUnit.

2. Select channels, ranges and AC/DC coupling using ps4000aSetChannel.

3. Use the trigger setup functions

[1] [2] [3] [4]

to set up the trigger if required.

4. Call ps4000aSetDataBuffer to tell the driver where your data buffer is.

5. Set up downsampling and start the oscilloscope running using

ps4000aRunStreaming.

6. Call ps4000aGetStreamingLatestValues to get data.

7. Process data returned to your application's function. This example is using Auto

Stop, so after the driver has received all the data points requested by the

application, it stops the device streaming.

8. Call ps4000aStop, even if Auto Stop is enabled.

9. Request new views of stored data using different downsampling parameters: see

Retrieving stored data.

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C-SCOPE R1 Guide d'installation Page 21