Thaum USB tau dhau los ua tus qauv, RS232 tseem siv dav rau cov tshuab luam ntawv qub hauv chaw ua haujlwm. RS232 raws tu qauv thiab cable tso cai rau lub computer muab commands rau lub tshuab luam ntawv ntawm ib tug voltage teeb liab. Lub tshuab luam ntawv ces deciphers cov lus txib thiab ua kom tiav cov ntawv luam tawm.
