[Nut-upsuser] apc with rs232

[grumpy at mailfence.com]

a friend gave me an old apc smart-ups 1250
it has a rs232 interface but i have no pc with a rs232 port
i attempted to use a rs232 to usb adapter but the ups goes nuts
i connected the ups to batteries and verified it was working properly
when i plug the usb cable into the pc the ups shuts down
when i attempt to turn it on it beeps twice and shuts down
this all occurs before i start the nut software
other than give up or buy a new ups, any suggestions