Maybe. But may I ask does it need to be limited to just a batch file that could be used on any omputer?
It is quite easy to do that in a compiled or interpreted language.
Such as VBS or QBASIC.
Also, when you say "1", do you really mean a break or mark or space. Or do you want an ASCII one to be written once to the serial output.
What baud rate?
What about RTS and DSR lines?
Look over the documentation the MODE command.
http://www.computerhope.com/modehlp.htm(See Serial port)
Please be more specific ans to what you intend and you will find lots of help thee.