The information provided here has been a real help. I'm adding cab lights and saloon lighting to a Farish Class 108 with DCC sound. It's been fitted with a Zimo MX646N in the power car. I tried to map FO1 and FO2 to F21 and F22 respectively as these are the first two function keys without sounds associated. However, I could get neither to work. I eventually ended up mapping the outputs to F14 and F15 as these keys just created a door slam / window slam so after that the output stayed live until turned off again. The decoder version is 33.10 so I expected to be able to use function keys above F20. As it turns out the trailer car is fitted with a Zimo MX681N function only decoder and as far as I can tell only allows function mapping up to F12 (no mention of swiss mapping in the manual for that decoder!). So that necessitated moving the sounds and functions from F14 and F15 to F8 and F9, again I found an excellent thread which described how to do this. Happy that all is now working but interested to know why I couldn't use the F21 and F22 as originally planned.
Regards,
Paul
