Recently I tried to do the chessboard calibration and the system seemed to be busy for quite some time. I could not get any reaction from the device, as if it did block somehow.
In good light conditions, the chessboard calibration will take 2-5 seconds, depending on the type of RyngDyng (RD720 is always faster than RD600 due to the stronger computer built in).
In case there are difficult light conditions, the processing times can be extended up to 1 minute. This is because RyngDyng will try various settings for the camera parameters in order to achieve a successful chessboard calibration. In any case, the processing will be signalled in your app by means of a rotating spinner at the top.
Also, when obstacles are hindering the sight of the cameras to the chessboards, this can result in extended processing times. If the chessboard calibration is not successful, this will be displayed by menas of the control images, see also this post: Chessboard calibration did not work.
We recommend that you run a test and provoke such an error in order learn and get used to this behaviour and reaction: Put an obstacle such as a piece of tape onto one of the chessboards and run the chessboard calibration. You will notice how long the execution time will be, and secondly how the control images by means of a red frame will tell you which chessboard could not be recognized.