Serial adapters/Linux/ModemManager

Some hosts include a USB modem detector, modemmanager, which opens any newly plugged adapter, configures it for 57600 baud, and transmits AT commands to elicit a response from a modem. This may interfere with use of a serial adapter. There are several workarounds:

• wait out the delay, and connect the coloured serial cable after starting screen,
• remove the ModemManager package, permanently preventing probe of USB modems, type this:

sudo rpm -e ModemManager && sudo killall modem-manager

• add udev rules to exclude the adapter, add this to /etc/udev/rules.d/01-local:

ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ENV{ID_MM_DEVICE_IGNORE}="1"

Affected hosts include:

• XOs with recent OLPC OS builds,
• Ubuntu,
• Debian.