USB Information
Universal Serial Bus - USB
This interface is a Bus. Think of it more like a network than a
point to point connection such as an RS-232 serial or "COM port"
connection even though it is most often used as one.
USB communication is done with "packets" of information like on a local area network.
USB has defined 2 types of connections "Hosts" and "Devices".
Hosts
"Hosts" control the bus and communications on the bus. The best example is our common Personal Computer (PC).
Devices
"Devices" connect to the bus and are recognized by the host. The host will determine when to allow the device to communicate on the bus. Devices include USB mice, flash drives, USB harddrives, scanners, etc...
The Elcom uTNC and uTNC plus are USB "Devices".
Summary
Because of the fundamental differences between RS-232 serial communications and USB, conversion can not be done with a simple wire cable adapter.
Intelligent adapters are available that connect to RS-232 serial equipment and a USB host to provide a one way "Device" to "Host" connection. We can not use one of these adapters in reverse to connect a USB mouse to the RS-232 serial port of a PC. We can connect a serial mouse to a USB "Host" with these adapters.
We can not connect a USB flash or "thumb" drive to a USB mouse and expect them to communicate. There is no "Host" on the bus. Add a PC to this bus and they can communicate. They just don't have a need to exchange information. But both now exchange information with the PC.
A lot of USB enabled "Devices" have serial communications internally that then use a USB interface chip to make the connection from the serial circuitry to the USB Host.