A2-19A-07-A1 is a part of Standard Communications Interface (SCI), which is a type of serial port used to connect external hardware (e.g. a modem) to a computer. A2-19A-07-A1 is a 9-pin male connector that supports 8 data bits and one stop bit when using asynchronous data communications. The pins include 5V, RX, TX, GND, RTS, CTS, DTR, and DSR. RTS and CTS are used for flow control, and DTR and DSR are used to signal the modem and computer when they are to reset or power down.