Absolute Beginner's Guide to A+ Certification

Touchscreen Interfacing to the Computer

Touchscreens, like ordinary LCD and CRT monitors, use the standard 15-pin VGA interface to the video card. However, the touch signals are transmitted to the computer through a separate interface known as the touchscreen controller. Touchscreen controllers can use any of the following interfaces:

• Serial (RS-232)— Some touchscreen monitors have an internal serial controller; others use an external serial controller. The internal serial controller might use a standard 9-pin serial cable or a special PS/2–to–9-pin serial cable to connect the controller to a serial (COM) port on the computer, depending upon the monitor model. The external serial controller uses a controller with a built-in serial cable. See ...