Internally, the PUP lights are virtually identical to the PF equivalent. Two resistors (series resistors for the LEDs - 510 ohm by the looks of it), two smoothing capacitiors, a bridge rectifier and a small resistor (2.2k) for ID.  A little smaller than the PF components, so values are a little harder to read on the capacitors, but I can't see anything particularly special about the lights. The series resistors in PF were 4.7k rather than 510 ohm, but when measured with a light-meter and run at full tilt, the PF ones are a tad brighter, using 7.2v of fully charged NiMh cells in each case.  I'm not particularly impressed, especially as they are significantly more expensive than the PF items. ID1 (pin 5) is pulled down to Gnd by the 2.2k resistor, ID2 (pin 6) is unconnected and the 9v line (pin 4) is not used.     Now, I'm assuming that the ID pins in the Smarthub have high value pull-up resistors so that an externally floating pin (as ID2 above) shows as a logic 1 and a low value resistor is used as a pull down to Gnd to signal a Logic 0. Obviously in a train motor, the pins are hard-wired (ID1 to 9v and ID2 to Gnd) so the ID logic for the motors and the lights appears to be reversed (Lights=x10 and Motor=x01).  Anyway, I'm possibly just going to open up a train motor to play with the ID's, or chop a PUP connector off the spare lights and hook it to my breakout board as the PCB in the lights is just way too fiddly to work with.  I have found another subtle difference between PF and PUP. If you set an output on PF (lights, train motor, etc.) then the output state is maintained until another IR command is received. For instance, if you start up a train motor on (say) speed 4 and then disconnect the PF motor from the receiver, when you reconnect the motor it will operate again at the last set speed. The same with lights - they will come on at whatever power level the channel was last set to. On PUP, disconnecting any load will automatically shut off the output of the port. Re-attach the lights or motor and the default state is off. It can be assumed then that checking the state of the ID pins is a continuous process and the ID isn't simply scanned at power on time. In that respect, the SmartHub Port is more 'intelligent' than the 'set and forget' output of the PF receiver.  Another part of my experimentation with my breakout board will be to try and change ID states 'on the fly' with lights or motors operating and see what effect that has on things.