I am trying to do some speed matching and consisting using DecoderPro and am getting unexpected results.
I have selected speed tables (not the basic speed control) method to play with speeds. I have adjusted my max speed down to a lower number (80) then applied the "match end points" to generate a straight line between the min/max speed. I have applied this to several locos and they operate as expected according to the values in the speed table. Then I use DecoderPro with same locos' to create a two loco consist under one address and this is where things go wrong.
When I try to control the two locos under the consist address, they respond totally differently from when I operate them independently. It takes at least 50% or more throttle to even get them moving and their top speed is not much more than a creep.
If I change the speed table back to a straight line (0-255), they respond (as a consist) more normally. It appears that the Vmax has somehow put a damper on the throttle response but it only does that when in a consist. No damper when the locos operate under their normal address.
How/why does the max speed table value adversly impact the consist speeds but not the individual locos speeds
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's
Yoiu did not say what kind of decoder you have. I will guess Digitrax because they are pretty much the only ones that have seperate Back-EMF settings for standalone and CV19 consist operation. That is what is causing your problem. The default is when using CV19 to consist it shuts off the BEMF, because at one time it was thought you had to do that oor the locos would fight one another. Maybe with Digitrax decoders - despite loving my Digitrax DCC system I do not like any of their decoders. I have BEMF decoders consisted all the time - even mixed brands, and they run fine together.
In DecoderPro, on the Motor tab for Digitrax decoders is an entry that says "Solo droop compensation". Whatever this value is, over on the Digitrax tab, put the same value in for "Consist droop compensation"
That should keep the response the same, consist or solo.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks Randy. I will jump on that tomorrow.
Wish I had a secret decoder ring like you do to uncover these obscure facts.
There's no secret sqirrel decoder ring, it's in the decoder manual. It's not particularly prominent because Digitrax by default doesn't use CV19 consisting, so a Digitrax decoder used on a Digitrax system never really sees the issue - the consist setting for BEMF applies ONLY to using CV19.
If you are using Digitrax decoders try setting CV57 to 102.
(If you are not using DecoderPro)
WS
Thanks Randy.
1) Yes, I am using Digitrax decoders
2) Making the droop values match fixed my problem. The factory setting for solo was 6. I don't really know what that value means but I set the Digitrax Consist value to 6 per your comments and all is well.
3) I was unaware of the existance of the Digitrax Decoder Manual. My bad. All I had was the guide that came with the decoders and it offered no info on this point. I downloaded the Decoder Manual so it looks like I have some more studying to do to get my decoders fine tuned to my liking.
I undertsand why they don't include that full manual with every decoder - no one else does either, the TCS instrction sheets just cover the basics, they too have a much more detailed comprehensive manual on their web site - it's amazing the things you can customize on them. You DO get a copy of the Digitrax Decoder Manual in a Digitrax DCC set, but that doesn't help much if you only buy the decoders.
This stuff really does get complex sometimes. Never heard of Droop Values before just now. Lost again....
-Tobes
There once was a simplified explanation of the 3 variables used to control BEMF (there are two other CVs besides this one, but they do not have different values for single or consist, because setting just this one to 0 turns off BEMF completely). To understand it fully requires understanding PID control theory which onvolves calculus. You can find a Wikipedia article if you really are interested. While I think I could still do the math if I took the time to read it, not everyone has been exposed to calculus.
Most any decoder with BEMF has this. The Digitrax decoder manual gives a goos way to tune your loco via trial and error (the useful range of values for the three CVs isn't that's great - it doesn't take much for the BEMF to make the motor MORE jerky than without). TCS and ESU decoders have an automatic tuning that matches the decoder to the motor. ESU's actually runs the loco, so you need a little room - don't try it on a short length of test track.