PicoScope 3000A Series Prog rammer's Guide 17
Copyright © 2011-2013 Pico Technology Limited. All rights reserved. ps3000abpg.en r9
2.7.4
Streaming mode
Streaming mode can capture data without the gaps that occur between blocks when
using block mode. Streaming mode supports downsampling and triggering, while
providing fast streaming at up to 31.25 MS/s (32 ns per sample) when one channel is
active, 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.
Aggregation. The driver returns aggregated readings while the device is streaming.
If aggregation is set to 1 then only one buffer is used per channel. When
aggregation is set above 1 then two buffers (maximum and minimum) per channel
are used.
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.
2.7.4.1 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 ps3000aOpenUnit.
2. Select channels, ranges and AC/DC coupling using ps3000aSetChannel.
3. [MSOs only] Set the digital port using ps3000aSetDigitalPort.
4. Use the trigger setup functions ps3000aSetTriggerChannelConditionsV2,
ps3000aSetTriggerChannelDirections and ps3000aSetTriggerChannelProperties to
set up the trigger if required.
5. [MSOs only] Use the trigger setup functions
ps3000aSetTriggerDigitalPortProperties to set up the digital trigger if required.
6. Call ps3000aSetDataBuffer to tell the driver where your data buffer is.
7. Set up aggregation and start the oscilloscope running using
ps3000aRunStreaming.
8. Call ps3000aGetStreamingLatestValues to get data.
9. 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.
10. Call ps3000aStop, even if Auto Stop is enabled.
11. Request new views of stored data using different downsampling parameters: see
Retrieving stored data.
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