Comment out the rule in /lib/udev/rules.d/95-upower-wup.rules

Or, if you don't run gnome, "apt-get remove upower" will also do the trick.

This wretched system repeatedly probes and soaks up data from your serial port causing reliable comms with FreeEMS to be impossible. It's VERY unlikely (approximating impossible) that this will cause any harm to your FreeEMS configuration, however it will drive you insane trying to figure out what is wrong as it's silent and insidious.

At this time, more than ONE THIRD of FreeEMS users have been screwed by this program. Don't be the next victim, remove or disable it now!

Also, lobby the author to get the rule removed: Send your complaints to Richard Hughes using this address: hughsient@gmail.com subject: "upower continuously corrupting comms"

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=586751

Fred.

This was fixed ages ago, demoting it from announce status now. But man did this package burn some serious hours while it was broken...