The UPDD Command Line Interface has a built in data capture function for this purpose.
To capture data run the command "upddutils recordraw" and draw a circle on the screen. This captures raw data coming from the touch device (when touching the screen) to a desktop file updd.raw or, since version 274, updd.raw.txt. Use Ctrl+C to terminate the data capture.
Note. In a multi touch device system you may need to pass the device n option on the command to capture data from the target touch device. The command upddutils devices lists the devices and their associated device handle.
Data capture example within Windows 10