If it doesn't work in Hyperterminal, then either the serial port settings are wrong or the cable is not wired correctly. For the driver to work, VISA has to be installed but Hyperterminal doesn't require it. There should be a menu option on the instrument to set serial port parameters (baud rate, stop bits, etc.), so you need to make sure that those settings and the settings for Hyperterminal match exactly. For the cable, double check the instrument manual but what you probably need is a null modem type. This type will connect TD on the pc's serial port to RD on the instrument's and RD of the pc's to TD of the instrument. For a DB9 to DB9 connection, this means pins 2 and 3 get cross-wired.
Allow to me to add a few personal observations
about serial communications in general. I have had more problems and spent more time on serial instruments than just about all others combined. Because no standards exist, everyone does things a little bit differently and it seems you're always starting from scratch. The only advantage I have is 25 years dealing with these pigs. The cost advantage of using serial versus GPIB may seem great but if someone has to spend close to a day debugging cables and settings, the cost savings are gone. The best way to deal with serial is to "Just say NO!".
Okay. End of rant.
