I have a program that sends data to a USB port in order to configure connected device. I have been wondering if it's possible to copy a single signal to multiple devices.

For example, this program sends specified data to COM1. I'm wondering if there's an USB cable that would be interpreted as COM1 and could be connected to multiple devices on the other end, essentially mirroring received data to all of them?

  • hardware wise no, but does this help (Windows cmd) for %L in (1,2,20) do program -p COM%i;done It runs the same program over again with different COM port numbers from 1 to 20 increments of 1.
    – cybernard
    Commented Feb 3, 2020 at 21:05
  • @cybernard this is a very cool solution - I don't think the program is capable of such thing but perhaps I could make a tiny AHK script. Getting a large USB splitter wouldn't be an issue.
    – xtl
    Commented Feb 4, 2020 at 8:41

1 Answer 1


No, but there are alternatives

Sorry for the short answer, but unfortunately, USB just doesn't work like this. Because of... protocol reasons that we won't dive into here, USB doesn't have anything really resembling this capability. The closest you'll get is a standard hub or KVM.

However, what does exist are serial splitters. Since it appears that all you're doing is using a COM port, what you could do is use a USB -> serial adapter, split the serial port into several serial ports, convert the serial back to USB (or whatever you'd like), and proceed to plug those into whatever target computers you're using. If that sounds like one too many adapters, StarTech even the ICUSB2324, a convenient USB to quad serial adapter.

However, there's a reason we don't all have USB and serial splitters plugged into our computers. There's almost always a better way of doing things, unless you're working with specialized, legacy hardware. Networking and virtual serial ports exist for a reason, and you're almost certainly better off using one of those. Without more info on your application I can't really say that with 100% certainty, but it's probably true.

  • Thank you. My devices usually use TTL connector, is there any splitter for it?
    – xtl
    Commented Jan 15, 2020 at 7:59
  • Not that I'm aware of, but I'm not super familiar with the platform, so there may be ones that I just don't know.
    – JMY1000
    Commented Jan 15, 2020 at 17:29
  • Note that the StarTech "splitter" you linked would enumerate as 4 separate USB-to-Serial devices behind a USB hub. That means the software would probably have to be rewritten to talk to 4 different COM ports as those individual devices probably can't all be bound to the same COM port.
    – Romen
    Commented Jan 17, 2020 at 21:10
  • @Romen Thanks for the clarification. I’ll keep it linked since it’s still a nice form factor.
    – JMY1000
    Commented Jan 17, 2020 at 23:09

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