The third serial port, sio2 (known as COM3 in DOS), is on /dev/cuaa2 for dial-out devices, and on /dev/ttyd2 for dial-in devices. Whats the difference between these two classes of devices?
You use ttydX for dial-ins. When opening /dev/ttydX in blocking mode, a process will wait for the corresponding cuaaX device to become inactive, and then wait for the carrier detect line to go active. When you open the cuaaX device, it makes sure the serial port isn’t already in use by the ttydX device. If the port’s available, it “steals” it from the ttydX device. Also, the cuaXX device doesn’t care about carrier detect. With this scheme and an auto-answer modem, you can have remote users log in and you can still dialout with the same modem and the system will take care of all the conflicts.
Related Questions
- The third serial port, sio2 (see sio(4), known as COM3 in DOS), is on /dev/cuaa2 for dial-out devices, and on /dev/ttyd2 for dial-in devices. What is the difference between these two classes of devices?
- The third serial port, sio2 (see sio(4), known as COM3 in DOS), is on /dev/cuad2 for dial-out devices, and on /dev/ttyd2 for dial-in devices. What is the difference between these two classes of devices?
- The third serial port, sio2 (known as COM3 in DOS), is on /dev/cuaa2 for dial-out devices, and on /dev/ttyd2 for dial-in devices. Whats the difference between these two classes of devices?
