Fine Tuned CV's Not Working When In Consist?

[tehachapifan]

Spent the better part of this evening fine-tuning CV's such as SV, back-EMF, etc, in a DTX decoder only to discover none of them seem carry over to when I assign the loco to a consist, where it runs with speed fluctuations when even by itself and with a way higher starting speed in step 1, especially in reverse. Got it running pretty sweet when not in a consist with a nice and slow creep in step 1 in both directions. Can't find anything about this in the manual or on the Web. What am I missing?

[GaryHinshaw]

Two questions: 1) What flavour of consisting do you use?  Advanced, basic, or command station assisted?  (Maybe just describe the steps you follow to set up a consist.)   2) Does the loco return to its tuned settings when taken out of the consist?

[tehachapifan]

Yes, the loco returns to its normal behavior when taken out of the consist. I set consists via universal consisting via the command station (not CV19). My experience with consisting is pretty minimal as only a branchline is currently set up with DCC and my consisting is usually limited to 2 road switchers, or a most often a road switcher with a soundcar.

[peteski]

That is odd.  The features of motor control such as speed tables or BEMF settings should be totally independent from addressing (or consisting) the decoder.  I wonder if it is something on the command station.

I assume that DTX is Digitrax.  What brand command station do you have?

[tehachapifan]

Yes, Digitrax decoder (DN163A3 for the MP15DC) and the command station is an MRC Prodigy Express. The other loco that I spent time speed matching this one with, and does not seem to have an issue when set in consist, has a Zimo decoder.

[tehachapifan]

OK, I think I may have figured it out as a CV57 programming omission. I originally only added a back-EMF value for a single unit (15) and did not originally add the value for when in an "advanced" consist (240). Strange thing is I thought I was using "universal" consisting and this particular value addition in CV57 was only for advanced consisting. At any rate, I now have 255 programmed in CV57 instead of 15 (max BEMF) and, so far, the loco is responding correctly when set in consist. Keeping fingers crossed!

[peteski]

Maybe you are somehow using advanced consisting after all?

 All that universal consisting does is to bundle several addresses together (in the command station) and simply send the control packet to those individual addresses in a synchronized way.  It is basically as if you had each of the models on a separate throttle and was able to tun the speed control knobs (and all the other function keys) all at the same time.  The decoders themselves "think" that they are being addressed as if they were lone-locomotives (not consisted in any way).

Advanced consisting works in a totally different way.  In that model decoder itself is "aware" of the fact that is being consisted.

Either way, I'm glad that you got things to work.

[nstars]

Are those fluctuations appearing when the loco runs coupled to another loco? If that is the case than switching of the Bemf is the solution. In that case the problem is quite simple, the 2 loco's are fighting each other trying to adjust their Beef to optimal performance. I have seen that happen before. Perhaps this behavior is adapted when used in advanced consisting.

Regards,

Marc

[tehachapifan]

Marc, I think it was a CV57 programming omission that did not carry over the CV adjustments when the loco was assigned into a consist (see above). The loco is running fine both in and out of a consist now.

Thanks!

[peteski]

Russ,
if you look at my last post here I asked about the consisting.  From Digitrax documentation about CV57:
The second hex digit of the CV value controls the droop in effect when the decoder is part of an advanced consist for speed and direction control. Values for each digit can range from 000 to 015 decimal or x00-x0F hex.

This CV setting only applies to advanced consists. You said that you used universal consisting (where the decoders are totally unaware of the fact that they are consisted).  Can you verify which type of consisting you are using?

See http://www.digitrax.com/tsd/KB575/multiple-unit-or-consist-operations-overview/

[tehachapifan]

I originally thought what I was doing was called "universal" or command station assisted, not "advanced" as the Digitrax literature seems to indicate. Still, for whatever reason, changing CV57 worked like a charm. Here's what I do with my MRC Prodigy Express. I hit the "Prog" key until the screen displays "Cons Set". I enter the locos when prompted and that's it. The only thing I can guess is that maybe these steps are affecting CV61 (correction, CV19) in the locos and, as far as at least the Digitrax decoder is concerned, has been set up with advanced consisting(?).

[peteski]

I originally thought what I was doing was called "universal" or command station assisted, not "advanced" as the Digitrax literature seems to indicate. Still, for whatever reason, changing CV57 worked like a charm. Here's what I do with my MRC Prodigy Express. I hit the "Prog" key until the screen displays "Cons Set". I enter the locos when prompted and that's it. The only thing I can guess is that maybe these steps are affecting CV61 in the locos and, as far as at least the Digitrax decoder is concerned, has been set up with advanced consisting(?).

The 3 types of consisting are clearly defined and work in totally separate ways.  CV61 has no settings which relate to consisting (other than maybe the headlight functionality).
CV61 Values: Non Directional Headlights, Transponding & Split Field Motor/AC


Easy way to check if you are using advanced consist is to take any of the locos still in the consist onto a programming track and read the values of CV 19. If it is anything but zero then it is in an advanced consist. http://www.digitrax.com/tsd/KB923/cv19-cv21-cv22-advanced-consist-addressfunction-co/

[tehachapifan]

Sorry, I meant CV19 (looks like I flipped 19 upside down! ) Actually, I was playing around with lighting CV's last night and must be where I got CV61 from. At any rate, I'll test the loco on the program track and see what it says. Been fussing with motor contacts on that unit today as this unit's been losing power to the motor....

...Ok, that's what's going on. CV19 says 003 and that's the consist number. So, advanced consisting is what I'm doing via the command station. Good to know!