"S" from Arduino to David
"S" from David to Arduino
Scanning process with changing the pattern starts
"T" from David to Arduino when last pattern was scanned
"Z" from David to Arduino when scan is saved
David starts now to align (if set) the scan
"2" from David to Arduino
Usually the turntable triggers the next scan by sending "S" (Arduino => David) and the whole process starts again.
Unfortunately David does not recognize/buffer the "S" from Arduino in case it is sent before last "2" message.
David should buffer the "S" from Arduino and start next round scanning when alignment is done ("2" sent from David to Arduino).
The bug could be also called as feature. Depends on the perspective of the things.

Thanks
Christian