It would be awesome if you could simply set a rolling capture window (i.e. 1 minute) and start recording. Then, the device would just keep the last minute of data (or whatever) and toss anything older. Sometimes it's tough to tell what you need to trigger off of. It would be great if we could just leave it running and hit stop after an event occurs and get the last n minutes.
Guest Jul 11, 2018
This is doable now with our latest beta software. Downloadable here:
1. Click Option -> Preferences -> set Pre-trigger buffer size to 60 seconds
2. Make sure your RAM can handle the incoming data at 60 seconds. If not, you will need to disable channels (especially analog channels). You can check estimated RAM usage below:
3. Set your trigger to positive pulse, 0 seconds min, 0 seconds max. This trigger is essentially unreachable, so the trigger condition will never be met, and the capture will continue to 'roll'.
4. Set your device settings to capture for something short, like 1 second.
5. Click 'Start' to begin recording. Once you are happy with it and you want to keep the last 60 seconds of your capture, click 'skip trigger', and you will record the last second of data.
Guest Jan 11, 2019
It's great that this is already possible with the beta release!
Can it also be done programmatically? E.g. if I run a script that detects a certain condition, can that cause the 'skip trigger' as well?
Tim Jan 11, 2019
Unfortunately, our automation scripting utility doesn't have a function that sends the 'skip trigger' command.
Though, you could set up an extra GPIO pin to toggle HIGH when that 'certain condition' has been met. If a GPIO pin was set up that way, you could monitor that with one of the Logic inputs and simply set up a positive-edge trigger (basically, you would modify step 3 from my previous post).
That way, the capture would continue rolling (say, 60 seconds of rolling data), and when the trigger is activated (GPIO pin toggles HIGH), then the capture would begin, and all previous 60 seconds would be kept.
We've already got plans to have this implemented much better than it is now! Sorry this solution is a bit cumbersome at the moment.