Connect to serial device?

[Rory Campbell-Lange <rory@campbell-lange.net>]

I'd like to connect to a multi-port UPS module via a serial port on my
linux box.

I have connected to the UPS module successfully using a Windows box and
the HyperTerminal program (on COM1).

What program would I use on my Linux box? Would I use /dev/ttyS0?

Thanks for any help.
Rory