2 digit or 4 digit?

[mreagant]

I have about a dozen locomotives that have decoders (have no record of what kind but likely Lenz or MRC) professionally installed close to 15 years ago.  At the time I was using an MRC Command 2000 system with its very limited addressing capability and they worked fine.  When I bought a PA Wireless a few months ago, most of my older decoder equipped engines made the transition easily, taking a 4 digit address corresponding to engine number.

A couple of them, however, did not and attempts to read back address or other information have not been successful thus far.  Neither have attempts to give them new, 4 digit addresses.  My question is, were some early decoders limited to 2 digit addresses, and if so how will I be able to tell?  Thus far with the PA I've used 4 digit addresses for everything, including one or two digit road numbers.  For example. Shay #7 is addressed as 0007.

I need some guidance here as I'm not sure how to troubleshoot beyond this point.  If it is simply a matter of setting a 2 digit address, I'm not clear how to do that.

Thanks.

[cacole]

 MRC decoders that old may not have even supported 4 digit addresses.  The first decoders I ever purchased were MRC that supported only a 2 digit address and 14 speed steps, and you cannot read back any CV values from them. 

[mreagant]

Thanks, I thought that might be the case.  So if I want to use them until I can upgrade, what are the steps for setting a two digit.  I guess I could first reset factory defaults (CV8=8 ?)  If that works I'll still want to set them to something other than 3.

[blrrfan]

actually, I suspect you have to use register mode, and use REG1 (matches CV1) for the address. Some decoders allowed to read back in register mode, just be patient. Some MRC decoders supported 28 speed steps, just like the command 2000 did (I owned both). Hence you may to want to try that, with REG5 (matches CV29) set to 2, else set to 0 (14 speed steps).

[mfm37]

 Use the method David posted to set a two digit address. Most if not all of those old decoders that only did short address did not have the reset feature either. That was introduced later.

Digitrax had a couple of decoders from way back that only had two digit addressing. DN93 and DH83 were a couple of them.

[locoworks]

mfm37

 Use the method David posted to set a two digit address. Most if not all of those old decoders that only did short address did not have the reset feature either. That was introduced later.

Digitrax had a couple of decoders from way back that only had two digit addressing. DN93 and DH83 were a couple of them.

can you use the alias method so that you dial in a 4 digit address to address a 2 digit address on the older decoders?? if you can? is it a digitrax feature only or do other manufacturers support this option??

[mfm37]

Aliasing was an option with Digitrax DCS100 and DT100 throttle. Other manufacturers may have/had it but not sure. Yes, Aliasing would work with a Chief system and DT100 throttle. Never tried to alias with a newer throttle but the DCS100 command stations still support it. Martin Myers

[mreagant]

Thanks to all.  David, I'll write directly to CV1 and see what happens.  The PA Wireless has an addressing sequence that does not require going through the step of calling up a specific CV, but I've only used it for 4 digit addresses and was uncertain if 2 digit addresses would stick using the address mode.

Thanks again.

[wjstix]

I recall that in many early decoder installation articles the writer would talk about using the last two digits of the engine's road no. as it's DCC address, so apparently for many years two digit was standard. Since I went DCC (2004) all the decoders I've bought have allowed for 4-digit using CV 17/18.