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    You aren't asking about RS232 to USB, but what happens when multiple devices are connected to the same USB port. They just work. That already happens on all computers and hubs. USB allows multiple devices on the same channel, and the ports on your computer are provided by the motherboard's internal hub. The host (your computer, RPi etc) exchanges USB packets with the devices. Commented Oct 13, 2025 at 7:44
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    FTDI on the other hand has a long history of quirks when it comes to USB-serial devices. They provide the chips and bare-bones reference drivers, that may miss functionality. When I used them (a long time ago, before SO) they didn't handle RTS/CTS automatically. I was surprised to find similar SO questions some years ago. I see you use both rtscts=False and xonxoff=False. How will the device know the RPI isn't ready to read yet? You could use a large input buffer so you don't miss anything until you check the port again, but what if the buffer is full? Commented Oct 13, 2025 at 7:56
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    Thank you for the information! One of the few things the device maker says in the documentation is that there is no flow control. I added to the question the code I'm using to read data (without some loops and tries), but I admit I built it out of other people's examples, because it was my first time. From what I understand, it uses the buffer and, for now, I never missed any data (because I more or less know what to expect). If I understood your comments correctly, does this mean that I can treat the two issues (reading from the device and using the hub) as separate? Sorry if I'm being dense. Commented Oct 13, 2025 at 10:52
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    USB is a bus. That's what the B in its name/acronym stands for. This bus is a data & control path for multiple (USB) devices to connect to a (USB) host. A (USB) hub is merely a (USB) device to provide more than one (USB) port to the host. Typically the host itself has a hub, aka the root hub. Commented Oct 14, 2025 at 1:56
  • Thank you for the explanation! I really need to do some reading. Commented Oct 14, 2025 at 7:01