Every once in a while I get a reminder of the good old days and the lingering quirks that have been passed down to us. The other day I was attempting to revive a couple old Lenz decoders that had been asleep for about 15 years. I plugged them into the ESU decoder tester, cranked up DecoderPro, and read back the addresses—103 and 104. I plugged them into a loco and put them onto the track. When I entered the addresses into my throttle I got no response. After checking the wires and the loco I finally put them on the service mode track and checked the addresses again, still 103 and 104. As the frustration mounted I was about to toss these old decoders and then something came back to me.
Well back in the infancy of DCC we only had 2-digit addresses—after all who would ever need addresses for more than 99 locomotives? However, because computers speak hexadecimal we were able to actually uses addresses up to 127. Because the addresses I entered were in the 1-127 range they were interpreted as 2-digit and not 4-digit addresses. And because I had set CV29 to expect 4-digit addresses the system and decoder were not communicating with one another. By simply changing CV 29 to a value of 2 which tells it to expect 2-digit addresses, I was in business.
Another relict of the past are the 2-digit advanced consist addresses. I don’t know anyone who likes them and it would seem more logical to be able to use the 4-digit address on the lead locomotive for the consist address but for some reason the NMRA DCC guys apparently can’t make the necessary changes to fix this anachronism.
Yesterday at an op session, a fellow mentioned that he had entered 4-digit addresses into his decoders and the locomotives wouldn’t run. When he told me the addresses I immediately recognized his problem. He had entered addresses of 9995 and 9996 assuming no one else at the local club would also be using those addresses. So what was the problem?
Well Digitrax, which was the system he was using, only supports addresses up to 9983 not 9999. I believe those address from 9984-9999 are reserved for use by the system. File that little quirk in the back of your mind and avoid those addresses.
That’s all the little quirks I can think of right now, but I’m sure more will pop up. I get several emails every day asking about odd happenings and I’ll add more later.