Opening logs

• Drag and drop a file onto the window.
• Open log… on the home screen, or the File menu in the Windows app.
• Double-click a log in Explorer. The Windows app registers as a handler for .hpl, .ld and .dl. Windows will not take a file type away from VCM Scanner or i2 by itself, so the first time you may need Open with → Choose another app → BigData, ticking “Always use this app” if you want it to stick. .csv is deliberately not claimed, because on most machines that belongs to Excel.
• History, on the home screen. Click any log you have opened before; rows saved to your account download and open on any device.

The file is decoded, channels are matched to known roles (RPM, throttle, lambda and so on), units are converted to US measures, and calculated channels are added.

Graphs are drawn from a reduced set of at most 12,000 points so panning and zooming stay quick, while histograms bin the full-resolution data underneath. That is why a table can report far more samples than the graph appears to contain, and it is deliberate: the tables are what you tune from. The header says “N of M rows” and notes that the display is downsampled whenever that happened.

A very large log is thinned even for the tables, above roughly 40 million values on a computer and less on a phone. The histogram toolbar then shows a downsampled badge, so you know the counts are of the samples kept rather than of the whole log.

Phones are lower because they have far less memory to work with, and the limit depends on the format because a compressed binary log expands enormously once decoded. The message always names the size of your file and the limit that applies, and suggests the website or the Windows app when a log is too big for the phone.

You get a message saying why, rather than a blank screen. The usual causes:

• The format needs exporting first. Some tools encrypt their own log container. See Supported formats.
• The file is too big for the device you are on.
• The log is cut off. A log that stopped mid-write often loses the block it was writing. Where the rest can still be read you get the log plus a note that it looks truncated.
• It is not a datalog at all, or it is a CSV with no recognisable time column.

If a log fails to open for a Palm Beach Dyno address it is uploaded automatically so the decoder can be fixed, and you do not have to send anything.