Experimental Physics and
Industrial Control System

> The databrowser is not able to display arrays, it only seems to grab scalar values from a record even if it’s an array of values it will only display index[0].  Therefore your data when you “Add PV” to the databrowser it will look quite strange if you were expecting your array to show up.

Arrays are used in at least 4 different ways. Via channel access you only get the array elements with no way to tell how to interpret them.

1) Packaging 'atomic' data.

Array elements are basically elements of a structure.

Element [0] may be a reading for 'channel 0', element [1] for 'channel 1', and the array is used to transfer consistent updates. The 'Index' property of a trace in the data browser selects the array element that's shown over time.

2) 'histogram' type data

Each waveform captures some data at a specific time, i.e. the one time stamp of the waveform reflects when the data was taken, and the array elements represent for example the 'bins' into which something was counted. No way to tell what the 'bin size' might be. In the primary data browser plot you just see the first array element over time. You can open the "Inspect Waveforms" view to see one waveform, selected by time, but again it's just the plain data  plotted over the array index. 

3) 'fast ADC' type data

The timestamp of the waveform represents the time stamp of the first array element, and the following array elements then show for example ADC readings taken at start + i*sample_period. For example, you might have one waveform per second with a per-element sample period of 1microsecond. Again you can look at the first sample over time in the main plot, and open "Inspect Waveforms" to see the details for each one.

In all those 3 cases, the data browser offers some way to inspect the waveform, but it cannot fully represent the data.

4) Images

Array elements are pixels of an image. Need to know the width, height and encoding. The 'Image' widget can be used to display grayscale and several RGB formats.

-Kay