what is going on with the raw trigger data?

[dmedine]

Why does the raw trigger data look like this:

raw_trigger_data.png (8.04 KiB) Viewed 20263 times

Close up showing expected shape of trigger with unexpected trigger values (and one of the intermittent huge negative spikes):

closeup.png (13.7 KiB) Viewed 20263 times

I would expect an integer value corresponding to the actual active pins on the parallel port connection. So two questions, what is the meaning of the huge negative floating point numbers and why the huge negative spikes every 5 seconds or so?

[Coen]

The samples are 24-bit words. The 16 least significant bits are the 16 trigger lines. The 8 most significant bits are used for system status, see https://www.biosemi.com/faq/trigger_signals.htm .

Best regards, Coen (BioSemi)

[dmedine]

That makes sense. Thanks for pointing me to the FAQ. Somehow I couldn't find the documentation for this.