I recently had the need to send AT commands to a USB modem while it was connected to a Mac using a serial interface. With no ‘terminal’ type application immediately obvious (perhaps I’m wrong?) I found this cunning use of screen to achieve the same results.
In my example, the serial interface is /dev/tty.wwan connecting at 9600 baud.
screen /dev/tty.wwan 9600
To quit screen use Control-A and then Control-\
Other available options:
cs8 or cs7
Specify the transmission of eight (or seven) bits per byte
ixon or -ixon
Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data
ixoff or -ixon
Enables (or disables) software flow-control for receiving data
istrip or -istrip
Clear (or keep) the eight bit in each received byte