title: Why can't I run two USB serial adaptors on the same machine?
body: <p>My work involves interacting with legacy hardware that uses serial ports. I often have to monitor more than one serial line, and for the purpose I have a couple of the common USB serial adaptors. When I connect both of them to the same (Windows 10) machine, irregularities show up. Both ports show up in device manager, but only the first one that I plug in to the USB connector works. The other one indicates port not open when I try to send data via RealTerm.</p>
  <p>I have also seen the situation where when I plug the second adaptor in, its port comes up, but the one for the other adaptor disappears. Does anyone know a way that two devices can happily coexist on the one machine?   Thanks in advance.</p>