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I want to mirror the data sent to (and/or from) a USB device to multiple host computers at the same time (i.e no physical switches to select one host or the other). Here are two scenarios to describe what I'm trying to do from a device's perspective:

  • Send Data: A USB microphone is hooked up to two computers such that when spoken into, the mic level on both computers increases simultaneously
  • Receive Data: An audio signal from each computer is transmitted over USB and "merged" before entering a DAC for external processing, effectively combining each computer's audio signal

My (limited) understanding of the USB protocol and other similar posts on StackExchange (1, 2, 3, 4) tell me that this isn't really possible, however, during my research on this topic I stumbled on these videos:

These seem to demonstrate that what I'm trying to do is possible, at least for sending data from the device. Can USB data really be mirrored in this fashion if it's done via RS232 connections? I've found the product page here, however I'm still skeptical of this and would like to see other examples of similar devices. Does anyone know what the generic name for a device like this is/know of any other examples of devices like this?

2 Answers2

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The device described in the video is perhaps similar to the USB Barcode Scanner Splitter (UBS-120P), however it doesn't help with your problem.

This works for RS232 sources, but you can't split USB signals like this. USB is a Serial communication device that employs a USB (Communications) protocol.

USB uses two way digital communication where the device talks to the computer to tell it how it can send its data to the computer. The computer and the device perform a handshake where they agree on the format of the data that the device will be sending.

You can't connect the same USB device to two computers at the same time, because the device cannot do a handshake with two computers. The most you can do is broadcast the audio to be picked by other computers via the network.

harrymc
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Those USB splitters are device specific. They work by decoding the input from a USB HID (human interface device) devices, splitting it out, and emulating duplicate HID devices to the connected computers. They will not work for anything other than USB HID devices. If you are wanting to mix and split audio signals then it would be far easier to do this with the audio than with the USB devices. If the goal is to maintain signal quality by keeping this digital as long as possible in the data path then doing so anywhere other than the USB part of the path would be far easier.

The use of RS-232 connectors on the devices you linked to has nothing to do with how the input signal is duplicated. The way they are using RS-232 is non-standard and is a good way to ruin hardware if someone wasn't very careful in using those cables.

MacGuffin
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