Engine Assignments in DCC

Model Railroader General Discussion (Model Railroader)
1

Ive been going over my BLI F7’s today happily programming CV’s in all it’s forms getting them ready for the next run.

I did run into one road block. Previously I learned how to assign addresses to each engine and then to consist them to a set that works together.

Now, my B&O F7 set is a ABBA unit. I think the A unit is #33 and the B is also a 33 but with an X. I could either give both engines the same address of 33 and leave em alone or give the B unit a different number.

I have another A-B with it’s own number set to complete the ABBA pair, but leave them out for the moment.

I discovered today giving the B unit a number like 34 is not a good idea. It sat mute on the program track until I hit the right address. I went ahead and did the total CV reset to factory default.

I would like to give this B unit a Helper or Slave Status. In the BLI manual that came with the engine they do provide painful instructions how to do it in analog mode. I went to the BLI’s website and pulled the QSI version three .PDF off the net and sat down to read it. I did not find what I was hoping to find, a nice chart of CV values that deals with engine role assignment.

Should I just give the B unit a address of 33 and leave it alone, treat the A-B pair like one big engine? Or should I learn how to give the B unit a slave or helper program input? Has anyone else been able to assign an engine with a value that will allow it to act in this manner instead of being just another Lead engine?

2

How about assigning them 331 & 332 numbers - unless you have 3 digit locos in that number series.[2c]

3

I guess it might depend on your DCC system. I have a BLI F7AB set, and have them numbered 37 (the numberboard on the A) and the B unit is 38.

With my NCE PowerHouse, or the new PowerCab, it’s easy to run “advanced” consists – I do it all the time. You don’t have to know anything about CVs.

But regardless of the system, as long as it will do “advanced consisting” you should get function sounds, like horn & bell, from only the lead unit, and running sounds, like notching and exhaust, from all. If the “B” unit is silent until specifically addressed, there’s something wrong somewhere.

The main consisting CV is 19. If it’s zero, the unit is not in a consist, and responds only to it’s own address; if there’s anything there, it’s in a consist, and only responds to speed commands sent to the consist. The consist number must be from 1 to 127; a unit running backwards will have that number plus 127 in CV 19. So you can put the same value in CV 19 of any number of locos and they’ll all respond to speed commands sent to that address.

You may want to mess with CVs 21 and/or 22 to make selected function keys respond to the consist address, rather than the lead loco address, but it’s not necessary, and I usually don’t bother. Dynamic brake, air brake, and mute are the only ones I’d use.

CVs 23 and 24 are used for acceleration and deceleration “adjustments”. I don’t think I’ve ever used them at all.

4

If they’re always going to run together - give them the same address. It’s much easier that way. I thought they did goofy things and made the B unit motor only, driven by the decoder in the A - or is that just the PCM FA’s? Anyway, the only problem with them both havign the same address is the horn will sound and the bell will ring on both units - unless you program the volumes on the B unit real low. Overall I think this is a much easier method than trying to consist them every time you want to run them.

If they do not always run together - you pair the B unit up with a different unit or something, then you will need to give eacha unique address. an extra leading or trailing digit is good, as long as it doesn’t conflict with some other loco in your roster. 331 and 332 as mentioned - unles you already have a 331 or 332.

–Randy

5

I have a P1K F3 ABBA set. Normally I run them as separate AB pairs but will consist them on occasion. I have replace the couplers between each AB pair with a drawbar so they will always be together. Logically they are one unit. The road numbers are 614A/B/C/D so the the first pair has been assigned 6141 and the second pair are assigned 6142.

6

I’ve got a P2K 0-6-0 with factory sound, QSI, I think. If the engine is put through the shut-down sequence, it will not resume engine sounds until I start it up. (Since this is a steam switcher, I haven’t felt the need to try consisting with it.) However, if I leave the engine on the tracks, without shutting it down, then the engine sounds will resume the next day if I have powered the whole layout off. I think the manual even mentions something like this.

Try leaving all your units powered and idling when you shut the system down for the night, and see if they will all behave the way you want the next morning. There may be a one-time requirement to directly address them after a full shutdown that you don’t have to worry about after that.

7

Thanks for the answers, it helps me think things thru a little bit.

The manual states that in Analog mode you can “scroll” thru and pick the specific function that tells the engine how to behave:

Lead unit. (All functions enabled)

Mid Engine, Slave Engine, Helper (Horn, Bell and reverse light disabled)

Rear Helper (Will obey reverse light direction, Horn/Bell in reverse [example A with another A unit] and as a steam engine behave on the rear of a train properly.

I can give them a 4 digit address but prefer to leave it at two because they might show up on a railroad that wont support 4 digit addresses.

My problem is seeing no clear chart or guideline to configure a engine unit to behave a certain way as part of a overall consist; this is most apparent when you are programming using DCC on the program track.

I see that it is possible to get down to each of the 8 bits on the binary level with each CV in the manual but if I want to go to all that trouble maybe I should just hook up the poor Tech 4 and hammer on that power pack’s switches until that little voice says the right words. “Engine Mode Helper” or similar. I like to use the on-board voice to read back the numbers and check with me as I fumble with the DT 400.

It is very annoying to have the B unit hit the horn when I want to use the A unit’s horn, turning down the B unit’s horn to zero is definately doeable but it’s not really solving the present issue.

When the A and B units recieve the address 33, they tend to constantly compenstate for each other and results in a little action that will eventually destroy the coupling.

With my PCM Reading T1 which is a lok sound unit, the chart of CV’s provided clearly assigns one CV with the different options such as Lead, helper, slave, rear pusher. I can program the T1 all day because the instructions are very specific, just like programming different sound volume options or even selecting one specific bell

8

As far as the functions in consist CVs (21 and 22), there is an NMRA RP covering those so the definitions from oen decoder to the next should be exactly the same. Thus you can make up the same chart for the QSI decoder as for the ESU decoder. Now, the sound of F5 for the ESU may not be the same sound on F5 for the QSI, but the CV setting that makes F5 work in a consist is the same between the two decoders.

See my post in the Layouts and layout building section for a how to on the bitmapped functions, how to mark the bits and convert to a number to program. Or just cheat and use the calculator accessory in Windows (if you use Windows) with the view set to Scientific. I know there are similar calculator applications in other operating systems as well.

–Randy

9

Bits huh?

Let’s see.

Maximum number expressed in Binary is 8 bits on IIIIIIII = 255 max.

Thus:

128, 64, 32, 16, 8, 4, 2, 1 = a total of 255

The tough part is getting to the actual bit.

10

I had my coffee this am and spent some time soaking in manuals. Here is what I understand so far.

The lead engine is usually the “TOP” engine on the right throttle on the DT400.

If the B unit has the same address the lead, the system treats everyone as one big multi-motor-decoder engine.

Problems occur when you mis-match engines… but let’s not go there because we are dealing with F7’s in A and B models. I COULD add a Roundhouse 4-4-0 to the F unit and have them work together but just thinking about that possibility generates a migraine.

Back to the orginal problem of Lead, Mid Train and Rear Helpers.

I want the B units to be a mid train helper.

Examining CV 21 reveals that the first 5 bits are on while the last three are off. The last three bits represents:

Coupler Crash Off
Whistle Horn Off
Bell Off

I wonder if I could simply write the Binary number of 248 (Representing the 5 bits on) to CV 21? That would work would it not?

I think I am actually more confortable with simply disabling coupler crash, whistle and bell on the B units because I know where they are on the CV chart for this engine. It would take a little longer but since I have time I dont mind.

Now… I thought that there was some kind of magic that needs to happen for the B unit to work with the A unit. Apparently There are two ways to run an engine’s motor in DCC. Standard Throttle Control which runs the Motor regardless of what load is on it. You set a speed and your engine will do that speed.

There is another way called Regulated Throttle Control which would respond to grades, load on the drawbar etc. and provide a way to share the power among multipule engines in a consist. I will have to check the manual on these F units to see if this feature is supported.

I might as well tackle the 4 digit addressing while im at it. The first engine is a 233 for the A unit and the B unit shows a 233-X. DCC does not do Letters so I think if I use

11

Remember place value starts at the left. So if by the first 5 bits are on and the last 3 are off you mean 11111000 and not 00011111, then yes, 248 is the decimal value you would write to CV21. The numbering is bit7-----bit0.

–Randy

12

Oh my.

Im trained to count bits from left to right this: 11111000 - 248 of a possible 255.

Heck I’ll give it a try once. I can always reset the durn thing. I’ll be back to let you know if it worked.

13

Well yes, you count them from left to right when converting, just like you mentioned: 128, 64, 32, 16, 8, 4, 2, 1

But when you talk about a specific bit being on or enabled: 00000001 is bit 0 on. 10000000 is bit 7 on.

–Randy

14

Yes I savvy it now. Always something to teach a old horse like me.

Cheers

15

I had a similar situation with a 4 unit Stewart FT ABBA. What I finally ended up doing, and I recommend documenting everything is as follows: since the units AB are drawbarred together and B is running bacwards, I use a credit card under each set of trucks I don’t want to change, and program the units separately. Since one of my B’s is a dummy full of sound, I program it separately with no acceleration/deceleration, and on the powered units I set the acceleration and deceleration CV’s at around 8 to 10. What this does is allow for inertia. Open the throttle a notch or two and the sound picks up before they start to move! Note that some of your units may be running in reverse! But I do use the same engine number for each unit - basic consisting! Enjoy! jc5729

16

Im not yet ready for inertia just yet.

I do hope those credit cards are those that typically come as a dummy without any value on them in the soliticator’s mass mailings.

I dont have any dummies, all 4 of my F units are individual locomotives in thier own right. Maybe I am a dummy but I tend to pass on engines that carry a dummy B unit instead of making them powered as well.

However I think PCM helps by having a decoder in the lead unit controlling both A and B’s motors with a wire harness between them. If I had that I would deal with just two decoders instead of 4.

I had a A B set of F units with just one power truck which ran very well for a LONG time. But part of the problem was the B unit looked good but weighted like 3 pounds cutting the ability of the A to pull by over half. Since I had a 4x6 loop at the time I was told I dont need a powered B (Roughly 12 dollars more at the time) that is one of the reasons why I enjoy full power across the entire consist today.

17

Randy,

I have looked in Layouts and Layout Building for you ‘how to on the bitmapped functions’. I couldn’t find it. Can you post a link to it. Please.

This part of DCC has always been a mystery to me. This thread has turned on a glimmer of light for me. I have a DSX sound decoder that has functions that have to be set by the bit. I think.

I would like to read your tutorial and see if it will finally explain the procedures for me.

Thanks in advance!

18

Well, it wasn’t a tutorial on how to use bitmapped functions, it was more a how to on converting binary to hex and decimal, and why using hex is actually easier.

However, since it sounds like a good idea, I will do a tutorial on bitmapped functions.

–Randy

19

In the meantime, here’s the message i was referring to:

In fact, even if your system cannot hook up to a computer, you can use DecoderPro to set CV values - indirectly. After you make all the changes using the easy check boxes and drop downs, there is a final page that will show on screen all the CV values that will get written if you actually could press the WRITE button. It also conveniently changes the color of any CV that needs to be changed, so you can see at a glance what would be changed.

CV29 is a special animal, and it’s one of the NMRA specified ones, so you can’t blame the manufacturers. The purpose is to switch on and off various options, so each bit in the value represents a different switch. Converting binary to decimal is a real pain - even I have to think about it for a while. But binary goes to hexidecimal very easily - just put them in groups of 4. This applies to any CV that uses different bits to mean things - many of the lighting effect CVs are like this: bit 0 = normal light, bit 1 = Mars light, bit 3 = rotary beacon, etc. (not actualy values that I know of, just an example). Remember that Bit 7 if the left-most bit and bit 0 is the right-most. So if by reading the documentation you find that to get what you want it says to set CV999 bits 2, 5, and 6, you write it out as 0110 0100. That’s bits 2, 5, and 6 set to 1. Every 4 bits is a hex number. There is NO grouping of binary bits that equals one decimal digit. This is why I say hex is MUCH easier. So convert each group to a hex number: 0110 = 6 hex and 0100 = 4 hex. How did I get that? Remember place value from elementary school? In the decimal system we have 1s, 10s, hundreds, thousands, etc. In binary, it’s 1s, 2s, 4s, 8s. So for 0110: 0 8s, 1 4s, 1 2s, and 0 1s (ok that’s hard to read maybe). Add them up - 0 + 4 + 2 + 0 = 6. You can see that it would be possibl to make a number where the sum adds up to 10 or more. That’s why in Hex there are the letters A through F = 10 through

20

Randy,

I really appreciate your taking the time to help.

I have downloaded the Digitrax DSD Owner’s Manual and Technical Reference from their website. Parts of them apply to the DSX decoders and the DSX 150 Manual as well. Though they purport to tell the owner how to program the decoders, they make the rather large assumption that he/she is familiar with hexadecimal programming.

As I mentioned I have tried to make sense of it and this thread has put a little light on the subject, but at least in my case, a larger flashlight is needed.

I will read and reread your message about CV29 and glean what I can from it.

I am looking forward to your tutorial.

Thanks again, many times over.