Digitrax decoder CV values (Digitrax for dummies)

[Cajonpassfan]

Sorry if this is a stupid question.I have two BLI F3 ABBA sets, with the B units being “dummies”. I like them,, but they could use a bit more power on my mountain railroad. So, I decided to use the BLI B unit shells on some spare Intermountain F unit power chassis I have. With very minor trimming, they fit just right. So far so good.

Next I popped a Digitrax DN163/1C decoder I found in my stockpile into the IM unit....took about 20 seconds. Works great. But...
now I’m trying to speed match the Digitrax B unit IM to the BLI A’s. This being my first Digitrax decoder install, I am baffled by the CV values terminology. I’m used to input a value between zero and 256 into CV 5 V Max (to limit top speed to 50smph) but the Digitrax instructions call for something like 098/x62....what I only own two Digitrax decoders and don’t plan to buy more so I don’t want to go to Digitrax university to become an expert at it, just want these two B units to match my BLI’s. Could I get some help here please? I run in 28 steps, the top should be 50mph and mid 25. What are the approximate values to program and tweak?

Assistance appreciated,
Otto K.

[peteski]

Digitrax is old-school (going back to times when CVs were programmed in Hex numbers, and understood by computer geeks.  When they mention any CV values, or ranges of values, the notation they use is DECIMAL/HEX   So the 098/x62 means a value of "98" in decimal (which equals "62" in Hexadecimal notation).

But other than the strange representation of the CV values in Digitrax manual, CV2, 5, and 6 will work just like they do with any other decoder.  That chart just shows some representational values Digitrax used for those different types of locomotives.  The other page you uploaded shows that the range of values for those 3 CVs is 000/x00 to 255/xFF. In modeler's speak 0-255

Also, the values in CV2, 5, and 6 do not directly represent any "scale MPH" values (in any decoder brand).  Since Digitrax uses different motor control circuitry than other brand decoders, you will have to experiment with those CVs to get a decent speed match to your other locos.

[Cajonpassfan]

Thanks Peteski, that makes sense, I appreciate your quick response. I should have been able to figure out the dual values, but it was late last night And yeah, I know the numbers don’t represent any particular speeds, but thanks for being thorough as you typically are (I did title this Digitrax for dummies). I’ll try to play with it later today to see if they play nicely together.
Otto

[carlso]

Otto
Peteski

There needs to be a "DCC for Dummies" manual. Actually, as I think about it I believe I had one put out by "Loy's Toys" back in the 1990's.

[Cajonpassfan]

Well, success, see below. Tweaked the CV’s, 2, 5, and 6 to get a pretty good match with the BLI’s. Running them parallel on the double track speedway at Verdemont, a cab in each hand set for different address. Takes a bit of hand/eye/brain coordination... Now onto trying to match the substantial momentum settings. The Accutrack speedometer is invaluable for this.
If anyone is interested, I set the top speed for my passenger power at 50 smph, the maximum passenger speed permitted on the lower end of Cajon Pass in those days. For this particular IM F unit and decoder, the respective values are 15, 84, and 35.don’t car what they are in hex...
Thanks for your interest,
Otto

[Steveruger45]

Otto
Peteski

There needs to be a "DCC for Dummies" manual. Actually, as I think about it I believe I had one put out by "Loy's Toys" back in the 1990's.

No need, we already have Peteski.