Digitrax FX3

Yesterday I spent a few hours trying to figure out how to use the FX3 features of my Digitrax decoder. My goal was to have the head and tail light of my switcher flash alternately in an attempt to indicate the strobe light that I have seen on the cab of many passenger engines as they pull a string of coaches past the platform. It took a through look through the Digitrax mobile decoder manual and some experimentation but I got it to work.

I started off setting setting CV49 which controls the front light to 036/0x24: single pulse strobe as a non direction effect phase A. The control for the back light, CV50, was set to 052/0x34: single pulse strobe as non direction effect phase B. The manual listed the options out as hexidecimal digits, I had to combine them to find the hexadecimal value that should be set, and then convert that into a decimal value to program it through the Zephyr command station. Luckily there was a hexadecimal conversion table at the back of the manual; however; it would have been easier if they provided two decimal numbers and just had me add them.

After I got the CVs set I moved the locomotive to the powered track to see if it worked. It worked halfway; only one light worked at a time. The front light flashed and the rear light was off when the locomotive was moving forward. When in reverse the rear light worked and the front light was dark. The solution was with CV33 and CV34. The manual describes these as "Function(s) controlled by F0F" and "Function(s) controlled by F0R". They were set to 001/x01 and 002/0x02 respectively. I didn't see anything in the manual about the settings for these but my suspicion was that they were a bitmask which mapped the function inputs from controller to to the FX3 functions. Eg. CV33 (F0F) was set to activate the first FX3 function (white front light) defined in CV49. I set both CV33 and CV34 to 003/0x03 so that F0F and F0R would activate both the white front light and yellow rear light (the color being the standard DCC decoder wire color, not the color of the light). This produced the desired result. The head and tail light would flash alternately as the switcher moved down the track.

Overall I was impressed that I could configure the lights to operate like this, however I wished that the documentation gave a better overview instead of just the detailed example on what values to use for ditch lights.