Connect your KAT500 via a KXUSB USB to Serial Adapter to your computer. Plug the 3.5mm TRS plug into the lower jack on the KAT500 back panel.
Choose the serial port that is connected to your KAT500. Click the down arrow to show the list of available serial ports and then select the serial port you have connected to your KAT500. See Finding the appropriate serial port for a USB to Serial Adapter if you're using a USB to Serial Adapter and are not sure which port to choose.
Click to update the list of available serial ports, which may be helpful if you plug in a USB to Serial Adapter after the program has started.
Reopens the serial port and verifies that the KAT500 Utility can communicate with your KAT500 and determine its RS-232 speed.