Ops mode programming revisited

More and more I find myself using ops mode programming on the Piedmont Southern. It is just so much easier to leave the locomotive on the mainline instead of maneuvering it to a programming track. Plus it is the most reliable way to program most decoders. But there seems to be a lot of misunderstanding with respect to ops mode programming. Ops or operations mode is also commonly known as programming on the main, which is one place programming can take place. Basically it allows you to program decoders without having to move them to a separate programming track. The downside to it is you can’t read back the settings of the CVs in the decoder, so you are sort of programming blind. However you can immediately test the locomotive’s response and know whether your programming was successful.

I often hear folks say that it isn’t safe to use it since you can reprogram all the locomotives on the layout, something that is totally false. Ops mode programming works by sending the programming commands ONLY to the decoder address that you select on the throttle. Consequently only decoders with that address will be reprogrammed, and any others on the track will simply ignore the programming commands. Service mode programming will reprogram all decoders on the service mode programming track–that’s why you have to isolate the service mode programming track. Part of this misunderstanding may stem from confusion over the difference between these two modes.

Another source of confusion for some folks is the fact that some DCC systems use the output contacts for both track power and service mode programming. With these you have be careful what you are doing and install a DPDT switch that will allow you to switch the output from the command station to either the main track or an isolated service mode programming track. I have explained how to do this in both my books as well as articles the past. In addition NCE sells the Auto-Sw which will automatically switch from the mainline to the programming track when you are in service mode–a great option for these limited output command stations.

Another possible source of confusion is that in the past different decoders have supported ops mode programming to different degrees. For example some did not allow you to reprogram the address with ops mode. However, to my knowledge all decoders manufactured today fully support ops mode programming and I have reprogrammed 2 and 4-digit addresses as well as various CVs using ops mode programming.


  • The thing I like about using ops mode programming is you can change sound settings and then immediately see the result. If you don’t like what you have done you can continue to change the setting until you get it like you like. The same goes for speed matching. I usually use service mode when I have installed a new decoder in a loco to test and make sure that the install went well. Once I am sure that it is responding correctly I immediately put the loco on the mainline and continue to program using ops mode. Just my take on things.