Let me just say that your simple example opened up a whole new understanding of the inner workings of OctoPrint. I am new to neither electronics, software nor Raspberry Pi but the OctoPrint documentation had me going in circles. In 15 minutes I soldered up a little 2 LED board to plug into my OctoPi (after modding the OctoPrint case I mashed up) and verified all of this. Now I am going to add solid state relays to the PSU and LED driver and get on with life. Thanks!