Hello, First of all: Thanks for your plugin. It really brought me into tinkering with microcontrollers and serial communication. Now to my problem: Is your mod working with 0.24.2? I experience the same issue Mulbin had. With 0.23.5 Everything works as intended, as soon as i fire up my 0.24.2 i get the "RX constantly flashing, TX dead" behaviour that is described earlier in this thread. I tried the following: Removing all mods except KSPSerialIO Changed the delay in the config (up to 40 seconds, confirmed new value via debug-console in main-screen) Changed baud-rate Changed value of #define IDLETIMER Changed value of #define CONTROLREFRESH Tried 0.24.2 32bit and 64bit I receive the message, that the COM5-port is used (correct port), as soon as the scene is loaded and then the RX-flashery starts. Here is the KSP-Log of my (unmodded) 0.24.2 Game: http://pastebin.com/hFqVR3Tk Any hints on what this may cause? Any help is really appreciated