I had a customer ask :
What is the different between 2 models below?
SCT3250EX-21.8"-EX112 (P/N 98-0003-3489-0 ND) W
SCT3250EX-21.8"-EX111 (P/N 98-0003-3490-8 ND) RW
In regards to the difference between the two touchscreens, the -0 suffix calls out a serial interface and the -8 suffix calls out a USB-R interface.
You can find the information on the series drawing.