# Port

Connect your KX3 via a KXUSB serial data cable to your computer.

### Serial Port

Choose the serial port that is connected to your KX3. Click the down arrow to show the list of available serial ports and then select the serial port you have connected to your KX3. 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.

### Refresh Port List

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.

### Test Communications

Reopens the serial port and verifies that the KX3 Utility can communicate with your KX3 and determine its RS-232 speed.

If you change the KX3's RS-232 speed using the KX3 front panel CONFIG:RS-232 menu selection or by entering a KX3 command in the Command Tester, use this button to allow the KX3 Utility to discover the KX3's new speed.

Note: If the KX3 is already loaded with MCU firmware (as indicated by a VFO frequency in the KX3's LCD display), it should respond to Test Communications with an "Information" dialog indicating that the KX3 is running the "Main" program. The speed shown should match the KX3 CONFIG:RS-232 menu selection.

If the KX3 is in a "Boot Loader" state, as indicated by the letters "MCU LD" on the LCD display, the KX3 should respond to Test Communications with a "Warning" dialog that looks like this:

If the KX3 has a running MCU (as indicated by a valid VFO A display) and Test Communications results in this Warning dialog, the KX3 Utility is not communicating with the KX3.

A KX3 in its boot loader, modems, null modem cables, and defective serial cables can echo whatever is sent to them. The KX3 Utility cannot tell what device is attached without sending a block of firmware. If MCU firmware load fails on the first block (address x800), it is very likely that the communications cable is not correctly attached to your KX3, the cable is defective, or the wrong port has been chosen.