How is Hyperterminal Working, regardless of port settings?

Question

I am trying to connect to a Quectel GNSS device that creates a virtual COM port in windows. I have always assumed these virtual devices work like a standard RS232 port with a fixed baud, however I have observed that when I connect to this port using Hyperterminal, it does not matter what settings I have, the data still streams normally. The baud can be anything, the stop bit can be anything, nothing changes the data stream.

Maybe I have always misunderstood how Hyperterminal works, but how is this device and virtual COM port able to work, regardless of the settings.

I realize this may not be the most appropriate place for this question, however I am shooting in the dark since it could be a protocol question related to EE topics.

Answer 1

It's not about how Hyperterminal works. It's how the virtual COM ports work.

Hyperterm or any other program just opens COM port and sets the baud rate you select and does what you want with it.

But since the data does not really go through an UART but just over USB packets, there is no concept of baud rate or stop bits that applies when communicating with USB devices that look like COM ports.

So this does not relate in any way to TTL or RS-232 or even UARTs.

Virtual COM ports are virtual for this reason. They can be opened and data can be sent and received by programs that want to open COM ports. But in reality the driver that provides a non-physical COM port can do whatever it wants to send or receive data, such as send it over USB or Ethernet or patch it to another virtual COM port so you can have a virtual null modem between two Hyperterms running on same computer.

They just pass bytes, but not through via an actual UART that does have to work at some rate and use some parity and stop bit settings.