By default, most TiePie engineering measuring instruments work in scope or block mode. In this mode, the complete measurement is recorded in the instrument's memory. After the full record has been measured, the data is transferred to the computer. The next measurement is started after the data has been processed, therefore there are gaps between the measurements.

Besides working in block mode, some TiePie engineering instruments, like the Handyscope HS3, Handyscope HS4, Handyscope HS4 DIFF, TiePieSCOPE HS805 and Handyprobe HP3, support streaming mode. In this mode the measured data is transferred directly to the computer, without using the internal memory of the instrument. This makes it possible to perform continuous measurements without gaps.

Both block and streaming measurements have their advantages and disadvantages. The key features of both modes are listed below.

• Block mode (or scope mode):
  • Fast measurements are possible
  • Record length is limited by the instrument's memory size
• Stream mode:
  • Long measurements are possible
  • Sample speed is limited by the data transfer rate to computer and the computer speed

In block mode, the next measurement is started after the previous data has been transferred to the computer. This means that there will always be a (small) gap in between the measurements. In streaming mode, no data is missed. All successive data blocks can be connected to form one big measurement.

A disadvantage of the streaming mode, is that the maximum measurement speed depends on the data transfer rate from the instrument to the computer, and on the overall system performance.

By default, most TiePie engineering measuring instruments work in scope or block mode. There are several ways to set an instrument's mode to stream.

The easiest way to use the streaming mode is to use one of the quick functions: "Transient recorder". This function can be selected by clicking the transient recorder button on the quick function toolbar or by selecting it from the quick functions menu. This function will set the selected instrument's mode to "stream". Besides this, for each channel of the instrument a data collector I/O object is created with a data size of 100000 samples and each data collector is put into a graph.

To manually change the mode of an instrument, click the measure mode button on the instrument toolbar to toggle between block mode and

The measure mode of an instrument can also be changed by using the popup menu of the instrument in the object tree. In the menu, select "Measure mode->Stream" or "Measure mode->Block".

Note: To change the mode of an instrument, the instrument must first be set to pause.

In streaming mode, the measured will arrive in blocks. Each of those blocks contains record length samples which are sampled at sample speed. These two settings determine the time it takes for a block of data to be measured, which is also the time between the arrival of two consecutive blocks.

Each time when a block arrives, the computer will process it and, depending on what is connected to the channel(s) in the software, perform mathematical operations with it, show it in a graph and/or store it to disk.

When the time between two consecutive blocks is short (the update is rate high), there is a risk that the computer is not able to process all data before the new block arrives. This may result in lost blocks of data or the streaming measurement being aborted.

It is recommended to keep the update rate lower than approximately 10 updates per second (a block measuring time larger than 0.1 second).

In streaming mode, successive measurements will arrive in blocks. Each of those blocks contains "record length" samples and can be connected seamlessly with previous and next data blocks.

The Data collector I/O object can be used to collect the successive measurements and combine them into one big block of data of up to 20 million samples.

All I/O's and sinks in the Multi Channel software support both block mode data and streaming data and can therefore be used in all situations.

Storing streaming data to disk can be done with the Disk writer sink. It can handle multiple streams directly, without the requirement of a Data collector in between.

Streaming measurements can be performed with the following TiePie engineering USB oscilloscopes: Handyscope HS3, Handyscope HS4, Handyscope HS4 DIFF, TiePieSCOPE HS805 and Handyprobe HP3.