A member of our scientific collaboration designed a data acquisition box with with 4 channels @ 1 kHz that synchronizes time with GPS. He uses USB 2.0 to have the box communicate with a computer, and the COM serial interface with a baud rate of 115200 is used to transfer data to the computer in ASCII format. The manufacturer calls this "virtual serial" over USB 2.0. Consequently, all configurations such as parity, workflow control, etc... does not matter in the serial interface, but only the baud rate has to be set to 115200 for this to work.
My question is: Does this number 115200 really represent the number of bytes per second that can be maximally transferred through this port, creating a limitation of what the USB 2.0 port can do? Or does this number really not matter and the real transfer rate is about 480 Mbits/s as standard USB 2.0?
What are the factors that decide this?
Why asking? The box currently uses uni-directional serial communication to deliver data, which causes problems of losing bytes some times on computer overload. The reliable solution would be to make the connection bi-directional with checksums and ask for packets and re-ask when data is corrupted. However, if we're really limited by 115 kB/s, this means we cannot transfer 4 channels @ 1 kHz.
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