I would like to find out what you need to do different when programming BEMF into Digitrax decoders that are being used into a advanced consist. I am using a NCE system. I see it has something to do with the first and second digit of CV57 But I don't have any more information in the look I was looking at.
I'm pretty sure in advanced consisting there isn't a way to change the BEMF. You can change the BEMF of the engine itself but that will be the same when you advance consist it. In my case my consists are usually set and stay that way so I do a simple consist and address all the engines the same number and turn off the BEMF on all the engines. I've found that with the BEMF they tend to fight each other going up an incline.
Is this the feature that maintains a locomotive's speed at any given throttle setting? I had the opportunity to operate on Grant-sar's layout, and I beleive that he has the BEMF off, so the helper operations require more throttle finesse, and more careful train handling. It all adds up to a more realistic experience. You must constantly watch slack in your train, pay attention to the grade, sags, summits and level spots, in order to avoid having an "unpaid vacation"!
Here's an oddball in Alberta doing extreme-cold-weather testing of a new modification. sar's Peigan Loop: The "Snakepit" along Crowsnest Lake is a winding, sinuous alignment protected by tunnels, and sheds: Unassisted, a brace of Grande tunnel motors in sar's Tunnel 6 lead a manifest upgrade to Crowsnest Pass: Thanks for the show, Grant!
I am trying to help a guy that is not doing much switching of cars but is running several trains. Some of his track is 2% grades in a helix. When pulling 20 or so cars with a double head consist the train come almost to a stop going up and races down. He has to consist loco to have enough power to make it up at all. I was hoping that by adding the help of BEMF I could smooth out some of this speed veration for him.
I am not sure that BEMF will fix this--adding free-er rolling wheelsets to alleviate the friction in the trucks should help. I had a coal train with Accumate wheels and trucks, and once I switched to MT LP wheels, it rolls considerably easier. The original wheels in a 25 car train would hold itself on a 2% grade like handbrakes.
If the person you are helping hasn't touched the BEMF already then it's causing the issue. Digitrax decoders are factory set with BEMF on. I found with running up a 2% helix that the consists I had with the BEMF still on you could watch the trains pull, then slow down, then pull and slow down againist each other and caused the train to end up stalling in the helix. When the BEMF was turned off the engines would simply pull and not stall out in the helix anymore. I would suggest checking the cv's and seeing what they are set to and if the BEMF is on turn it off and try it again.
BEMF is not recommended for consists because it will pit one engine against the other. As one slows down, the other will sense it and try to speed up. This causes the engines to counter what the other is trying to do (as maverick0 alluded to). I would suggest you check with the manufacturer of the decoder, but I have seen nothing lately that changes the original recommendation. [edit] My slow typing prevented me from posting this before Maverick0 made his second post. Dan
So let me ask 1 more question. What if you had 2 loco and only turned on the BEMF for one of them? I understand why if they both had BEMF turned on you could have them fighting it out but with just 1 of them making adjustments the 2nd loco would just even the pulling out.
If you have one turned on, it will still fight the other if they are not precisely matched in speed. The other one (no BEMF) just won't be fighting back.
I think what I want is a fight. IF the train is moving slower then the BEMF engine wants it to it will pull harder. If it is getting pushed down the hill it will put on the brakes and fight back to slow things down. In a worst case it will spin some going up and slide some coming down but that is all in the setting up of others CV. I hope to give this a try Sunday I will let you know how it works out. Thanks Dan
Dan, Since you have an NCE system, if you don't already have it you need to get the Digitrax Decoer Manual. It comes with Digitrax systems and goes into more detail than the sheets that come with the decoders. It explains setting up Back EMF compensation on pages 58 - 60. CV57 controls the intensity for when in an advanced consist and when not in one. If you look at the hex value of CV57, the left digit sets the intensisty when in an advanced consist, and the right digit sets it when not in one.
I have that manual but I didn't understand the left and right digit thing. Also I do have a NCE system and as far as I know I can not program in hex. Does this mean I need to convert the hex into a real number and put it into my NCE system?
I assume by "real number" you mean decimal, a hexadecimal number is just as real as a decimal number. Yes, you do need to convert it to decimal. Ther is a conversion chart in the back of the Digirax decoder manual.
