Loop-back Test Procedure for checking your Serial ports or
USBtoSerial Converters
1. If you have a USBtoSerial Converter, plug it in.
If you using Windows XP and newer before install drivers please check follow this information:
http://info.kmtronic.com/ftdi-virtual-com-port-drivers-installation.html
If you using Windows 7, Vista, 8 ... wait until Windows install drivers automatically.
2. You should check Device Manager to see if it is there first!
After the drivers' installed, an additional COM port appears in the Device Manager of Windows - usually, it is COM3, COM4 COM5 ...
Then proceed.
3. Connect RX PIN to TX PIN only
4. Download and run Loopback Test Software:
http://www.info.kmtronic.com/software/KMTronic_Loopback_Tester.zip
5. Choose COM port, click Open, write word or symbol and click Send
If you see reply the same you send - CONGRATULATIONs!
Driver is installed correctly and hardware work.
http://info.kmtronic.com/ftdi-virtual-com-port-drivers-installation.html