On a PC, it's relatively simple to send commands from a DOS prompt.

Use the 'mode' command to set the port parameters:
mode COM1:9600,n,8,1 (sets port to 9600 baud, no parity, 8 data bits, 1 stop bit)

Using the copy command, you should be able to send the contents of a text file to COM1:
copy command.txt com1 will send a copy of the file command.txt to COM1