Most of these questions revolve around a "dongle" or a USB to RS-232 Serial converter.
If a Universal Serial Bus (USB) to serial dongle isn’t working properly, try the following:
- Make sure the cables are properly connected.
- Make sure you have installed the latest software for your dongle. Visit the manufacturer’s website for any updates.
- If the device is connected to a USB hub, make sure the device and the hub are USB 2.0 Hi-Speed devices.
- Disconnect all USB devices except the device you’re testing. Make sure the device is connected directly to the computer, and that any hubs or extension cables are disconnected. If you can use the device now, the problem may be with one of the other USB devices or hubs you had connected to your computer. Try reconnecting them, one by one, to your computer. When you find the device that causes the problem, review that device’s documentation for further troubleshooting steps.
- Switch the USB cable from the current USB port to another USB port. If you can use the device now, your computer might need to be repaired.