I have a device connected to USB port via USB cable to my PC and in device Manager it says - > "XYZ corp Virtual COM port (COM A)"
Is this is same as Serial Com Port.?What is the underlying hardware under it both at device side and Host Side - a Uart or a USB or both at either end respectively?
It sounds like your USB device uses a driver that provides a serial port interface inside your computer. This means that other software can use the serial port APIs that Windows provides to connect to it and use it as a serial port. That software doesn't need to know the details of your USB device; it just needs to know about using serial ports in Windows. Windows ships with a driver that is often used to do this, and that driver is named usbser.sys. Your device might be using usbser.sys or it might be using some other driver.
The serial data is transferred via your computer's USB port and a USB cable. If you look at the signals on the USB cable, you will not see typical serial signals: you will see regular USB packets that just happen to be carrying that data needed for a serial port.
The USB device on the end of that cable might then translate that data into serial signals and act like a normal serial port, or that data might just be used directly inside the device. Without a link to the product in question, it is hard to tell you more than that.
