Pico Communications PicoScope 2104 manual Advanced features, Sampling modes, More on block mode

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PicoScope 2104 & 2105 PC Oscilloscope User Guide

3.4Advanced features

3.4.1Sampling modes

A PicoScope PC Oscilloscope can run in various sampling modes. At high sampling rates, the oscilloscope collects data much faster than a PC can read it. To compensate for this, the oscilloscope stores a block of data in an internal memory buffer, delaying transfer to the PC until a preset number of data points has been sampled. This is called block mode. At very low sampling rates, you may want to switch to streaming mode. This allows accurately timed data to be transferred back to the PC, without gaps. Real-time continuous mode is also provided for use at low sampling rates, and allows capture of data from multiple converters.

Sampling mode support in Pico software

	Block	Streaming	Real-time
			continuous
PicoScope	Yes * †	Yes * †	No
PicoLog	Yes *	Yes *	Yes

*Only with a single converter

†PicoScope automatically selects block or streaming mode

3.4.2More on block mode

In block mode, the computer prompts a unit to collect a block of data into its internal memory. When the oscilloscope has collected the whole block, it will signal it is ready, and transfer the whole block into computer memory via the USB port.

The maximum number of values depends upon the size of the oscilloscope's memory. A PicoScope PC Oscilloscope can sample at a number of different rates, which correspond to the maximum sampling frequency divided by 1, 2, 4, 8 and so on.

The PicoScope 2000 Series driver normally performs a number of setup operations before collecting each block of data. This can take up to 50 milliseconds. If it is necessary to collect data with the minimum time interval between blocks, avoid calling setup functions between calls to ps2000_run_block(), ps2000_ready(), ps2000_stop() (not normally used) and ps2000_get_values().

PS2100044-1.0 Copyright 2006 Pico Technology Limited. All rights reserved.