I haven't used RaceChrono (upgraded version) in about a year, but I recall being able to select the OBD2 channels I wanted to record, and the rate they were sampled. I tried using it today and can't for the life of me find where to do that now. Version 6.4.1 is installed on my phone. From the main screen (big red start button), when I go to settings, I have my OBDLink MX+ selected, but beyond that, I can't see any way to configure it. Strangely enough, when I review one of the sessions I recorded today, if I go to a lap and select settings, there are 5 OBD2 reader channels available (Coolant Temp, Engine RPM, Intake Temp, Speed and Throttle Position), and it has recorded data for those channels. IIRC, those were what I selected the last time I used the app, but like I said, I can't figure out how to do that now.
I've searched around the Racechrono website, looking at all the FAQ's and tutorials, I've looked through this forum and elsewhere on-line and can't find any useful information. Either I'm blind or there's something missing. Any help is appreciated!