Unable to add Insteon PLM modem, "Could not connect to Insteon modem"

My 2413U PLM is connected at /dev/ttyUSB0 and I’m able to echo text out to it. Unfortunately, when I try to add it in Devices, I supply


to which it responds “Failed to connect”. That’s about all the log entry says as well, not other info.

Seems hard to mess up, and yet, here we are. Does anyone have an idea what might be wrong?

If I do a “echo >/dev/ttyUSB0 Hello” that works as expected, so the port is accessible. The hub works on a Mac with Indifo, so not sure what could be wrong!


Hi @davepl I assume you are using a Mac, correct? There are only 2 reasons I can think of that HA could not connect:

  1. /dev/ttyUSB0 is open by a different application (i.e. Indigo)
  2. The device on /dev/ttyUSB0 is not the PLM. When HA connects to the PLM it issues a command to determine the PLM information (GET IM INFO command). If this does not respond correctly it is not an Insteon modem.

I don’t know much about Macs so not sure what to say but to your point there is not a lot of ways to screw this up.