DH121 Problems

Model Railroader Electronics and DCC
1

I have some old locomotives with Digitrax DH121 decoders in them (yes, I know they’re old). I am having trouble reading and writing to the decoders with pretty much every system when I use JMRI. With my DCC++ system I get an error code, and “no response from the Decoder” in JMRI. I got the same response with my Roco Lokmaus system. If I bring my locos to my friend’s house and use his PR3 with JMRI, we get the same response. The only way to program these decoders is to put them on a programming track directly connected to his Zephyr, and program them manually.

Is this a Decoder problem, or a JMRI problem? Does this decoder need some help to work with JMRI?

2

Check what programming moode you are using. These decoders are old enough that they probably don’t support DIR or direct mode, just PHYS and PAGE. Paged is what you want. On a Zephyr, the display would show PAG when cycling through the program options.

–Randy