Why Crestron can use USB to RS232 adapter for programmatically control SX20

Version 1

    Why Crestron can use USB to RS232 adapter for programmatically control SX20 but have com port notebook cannot(use Putty and hypertrm)?

    I try speed 9600,38400,115200,but Putty and hypertrm is no report and cannot enter the function key .

    Can i use USB to RS232 adapter connect SX20 like MXP? have any questions is the need to pay attention to it?