2021-09-15 Linux, serial devices that aren't modems and modemmanager 3 days ago
I always noticed that I had to plug in the USB cable for the remote radio with the radio switched off, otherwise the Kenwood TS480 would switch into transmit mode and stay there until I powered the radio off. Annoying, and I thought it was something in the serial initialization. Recently I was thinking about this and remembered something about query sequences on serial devices triggering weird behaviour in other devices. From what I read about the Kenwood serial protocol the chance of a few stray characters changing something in the radio is quite possible. So I considered what Linux software could do a query as soon as a serial port is added to the system. Well, modemmanager was the ideal candidate for this:Package: modemmanager [..] Description-en: D-Bus service for managing modems ModemManager is a DBus-activated daemon which controls mobile broadband (2G/3G/4G) devices and connections. Whether built-in devices, USB dongles, Bluetooth-paired telephones or professional RS232/USB devices with external power supplies, ModemManager is able to prepare and configure the modems and setup connections with them.And indeed, simply removing modemmanager made the problem go away. I can now plug in the USB cable when the radio is on and nothing happens.