With the advent of function-only decoders, transponding/function-only decoders, and especially now that Throttle Up! has discontinued the DSD-150 line, forcing people to use the DSX if they want the full sound experience, it's becoming more and more common that people will have more than one decoder in a single loco. The problem with this is that when you program one, you're programming them all. Yet, each one has its own programming requirement. Without programming lock, you either have to provide a way do disconnect all decoders but the one you're programming, or develop a complex procedure to program them independently of each other via OPS-Mode programming. With programming lock, you can simply lock all decoders except the one you want to program.

When Train Control Systems developed their function-only decoder, to be mounted in a loco to supplement the functions of the regular decoder, it included a programming lock to allow it to be locked while you program the other decoder. While this was good (a start) I recognized the need for all decoders to have a programming lock feature for the two reasons cited above. At that time I proposed, to all the companies we deal with, that a standard lock feature be developed that all manufacturers would use.

While most companies were amenable to the idea, and Train Control Systems had already developed a working lock, Digitrax applied for (and received) permission to use a pair of CVs for experimentation with a lock system. Digitrax has since announced that all of their series "3" decoders have program lock. Further, they are presenting it to the NMRA to become a part of the recommended practices. I fully expect this locking method to become an NMRA RP that most manufacturers will use. If you think this is a good idea, petition your favorite decoder manufacture to implement it as well.

Here's how it works, using CVs 15 and 16 - both defaulting to zero (0).

CV16 is used to create a lock ID Number from 1 through 7. Programming any value from 1 through 7 locks the decoder. At this point, the only CV that can be programmed is CV15, via programming track or OPS-Mode - no other CV can be programmed. Programming the same value into CV15 will unlock the decoder for programming in Service-Mode (programming track) or OPS-Mode.

While zero could be used as a lock value, by programming a value of 1 to 7 into CV15, it's not a good idea - which will become obvious to you later as you read the rest of this.

Here's how it works: Let's say you have four decoders in your loco: an NCE decoder to drive the motor, a Train Control Systems function-only decoder for more functional outputs, a Throttle Up! (SoundTraxx) DSX for sound, and a Transponder from Digitrax.

First, NCE decoders do not have programming lock. Train Control Systems function-only decoders have a programming lock that works differently than Digitrax's, but I assume they will change it to match Digitrax's when it becomes an RP. I've been told that Throttle Up! is talking about including it, so we'll assume it has programming lock implemented in our scenario. Digitrax's Transponder only doesn't have lock today, but future ones will. So, in all, the only decoder without programming lock (which I expect to change in the future) is the NCE motor decoder - so we'll always re-program that one after programming any of the others.

Next you should devise a standard for locking various types of decoders that you may be using, and stick with that standard. This way you won't have to keep track of the ID number for every single decoder you have.

0) Digitrax recommends using zero as a non-locking value. That is, if you don't wantt a decoder locked, leave CVs 15 and 16 at zero.

1) Use a value (ID Number) of 01 for regular motor decoders. This way you always know to unlock #1 to program motor and headlight CVs on the main decoder.

2) Use ID Number 02 for sound decoders.

3) Use ID Number 03 for function-only decoders.

4) Use ID Number 04 for transponder-only decoders. This one isn't on Digitrax's list of recommendations, but it makes sense.

The rest of the values (05, 06, and 07) can be used for anything else that comes along new in the future, or for your own special needs.

If you stick with the standard set above, and everybody else does also, there will never be a question about how to unlock any specific type of device.

Since the NCE decoder doesn't have a lock, you can't lock it. But, the rest do (or will) have a lock. So, before you install any of them, you should put them on the programming track, thoroughly test them, program the desired address and anything else you know you'll want to program, then lock them with the appropriate ID Number. A Decoder Tester is handy for making this whole procedure quick and easy to do.

Once installed, and you're running the loco around the track for a shake-down cruise, you'll probably find something that needs to be changed: V-start on the motor decoder, and Volume on the sound decoder, for example.

Since the motor decoder doesn't have a lock, it has to be programmed last. So, first program a value of 02 into CV15. This unlocks the sound decoder. Since the function only decoder has a value of 03 in CV16, it stays locked because 02 does not match it. Ditto with the transponder which has a value of 04 as the ID code.

With the DSX unlocked, you can now program the volume or anything else that needs to be changed - on the programming track or via OPS-Mode. We recommend using OPS-Mode for this when you have two or more decoders that will be drawing power during the programming process. With the current limitations of some programming tracks, trying to program a sound decoder while powering others at the same time may not work. However, with OPS-Mode, current isn't a factor because all decoders will be getting full current from the track at all times.

Also, when you have a decoder that can't be locked, you need to keep track of which CVs you program on the "unlocked" decoder. Remember, the decoder that doesn't have the lock will also be getting programmed, and the values you're programming into whatever CVs you're programming could be problematic or detrimental to it.

Once you have finished your programming on the DSX, unlocking the next decoder will automatically lock the DSX. For example, if you needed to remap a function on the function only decoder, programming a 03 into CV15 will unlock the function only decoder, and lock the DSX and all other lockable decoders. When finished programming all lockable decoders, lock them all by programming a zero back into CV15. By not using zero as an ID Number for anything, you can always be assured that programming a zero into CV15 will lock all lockable decoders.

Now it's time to program the motor decoder - the only one without a programming lock. The first thing to do is review all of the CVs you programmed on the DSX, and other decoders, to see if those CVs mean anything to the motor decoder. If so, you need to re-program those back to whatever they need to be. Once that's done you can program V-start or any other CV needed on that decoder.

You can see how important programming lock is if you need to have two or more decoders in one loco. Hopefully, all decoder manufacturers will adopt this feature - real soon. If your favorite manufacturer doesn't adopt it soon, contact them directly to ask for it. Trust me, they will listen to you more than they will listen to your dealer.