Byte-width of the serial communication. The 8 in "8n1" for example.
Parity setting of the serial port.
Time to delay between each byte sent to the modem, in microseconds.
Number of stop bits for communication on the serial port. Either 1 or 2. The 1 in "8n1" for example.
Speed to use for communication over the serial port. Note that this value usually has no effect for mobile broadband modems as they generally ignore speed settings and use the highest available speed.