Decoder stopped programming

[JRP]

Hi everyone, I have a new NCE D13SR decoder I just installed on an Athearn GP38. I have been using the "speed table" to program it to run in a consist with another loco with Tsunami. I had just about finished programming the NCE yesterday (using both PAGE and OPS Mode) when I could not get a CVRD "read back" from the NCE on my booster (Zephyr). I get the "d nA" reading (no acknowledgement). I tested another locomotive right away and got readings back just fine and I get throttle response from both engines (the NCE is not wired for lights), but I'm not able to change a CV now on the NCE. I don't think there is anything wrong with the NCE decoder and the booster seems to be working. Any ideas from you experts in the group? JRP GSW&PR

[rrinker]

 Does the loco with the NCE run? d NA's are usually because the acknowledge pulse is missing. Either the wires are not conencted to the program track, the program track is dirty, the loco wheels are dirty, the loco pickups are dirty or the motor wires are not makign good contact with the motor.

 Since is sounds like another loco works fine, this rules on the program track conenction and generalyl rules out the program track being dirty.

     --Randy

[cacole]

The usual solution is to perform a decoder reset and start over.  On the NCE decoders, the reset command is CV30 = 2 on the programming track; remove power; put the loco back on an operating track, then try address 3 to confirm that the reset command was successful.

[JRP]

Yes, I'm aware of the reset, but in order to do that I need to read the last CV30 address and then change it to 2. It won't let me do that, and instead gives me the d nA reading. But the locomotive runs when I add power with the throtle.

[rrinker]

You don;t need to read the reset CVs, if the reset process is to set CV30 to 2 for that decoder, you just write it. THere's nothign already there to be worried about overwriting. Same with decoders that rest by setting CV8 to 8. CV8 is jus tthe manufacturer ID and it can;t be written, so the decoder firmware has logic in it to detect a write to that normally unwritable CV and reset all values to factory defaults. It doesn;t actually change CV8 (or CV30, in this case).

 

                   --Randy

[JRP]

We'll Randy, I tried that too but no go. It just will not re-set. Yet it runs fine on throttle response at the current address. I think what I need to do now is write NCE and ask them what they suggest. I just hope my Zephyr is not to blame, but I don't think it is. Other loco's CV's write and run fine. Maybe just a fluk in the decoder. Thanks JRP

[CNR378]

Did you accidentally lock the decoder?

Peter

[wjstix]

If you can read back the loco ID number on the programming track, and it operates OK under that ID no., I'd agree you may have accidently "locked" the decoder. Look at the instructions, it should tell you how to lock and unlock the decoder.

[JRP]

Too late to check anything now. I contacted the NCE factory and they said to ship it back (went today). My hope is they will give me a new one to start over with. But I was curious about "unlocking" the decoder. I had not heard of that before.

[cacole]

To lock a decoder:  If CV15 is NOT equal to CV16, decoder programming is locked and it will not program or read (except CV15).

If CV15 IS equal to CV16, the decoder is unlocked and the decoder will respond to programming commands.  CV15 is always programmable, even when the decoder is locked.

This applies to practically every brand of decoder and not just NCE.

[wjstix]

JRP

Too late to check anything now. I contacted the NCE factory and they said to ship it back (went today). My hope is they will give me a new one to start over with. But I was curious about "unlocking" the decoder. I had not heard of that before.

 

Locking the decoder is a way to save the settings you've made to the CVs so that they're not accidently changed later, say when programming another engine on the main. It's handy if you're piggybacking a sound-only decoder on top of a regular decoder. You can get the regular decoder set the way you want for motion and lights, then lock it and install the sound decoder. You can then program the CVs of the sound decoder without having to worry about accidently changing the CVs of the regular decoder.