Z21 Reading CVs on Dummy Class 800 fitted with DCC Sound

[Novco007]

Hi All,

 

I dont post very often as my layout was an OO gauge and on two portable tables as it could only be used outside, so I was limited to fine weekend between Late Spring to Early Autumn, and 2017 had very few fine weekends that I could do anything and 2018 I moved, which has now enabled me have my two tables up permanently, although I plan to put a permanent layout in over the next year(s).

 

But on to my immediate problem with my Z21, I haven't used it for ages and I purchased a Hornby Class 800 from Hatton's and had sound fitted to both power cars.

 

I had a load of issues trying to change the CV from 3 to another number, once I got it working, I realised that the sound was not working as it should, so for instance, the horn should sound from the loco at the front of the train, depending on direction, but it only works on one.

 

So I have been asked by Hatton's to check CV 29, but I can not get my Z21 to read the chip in the dummy unit, but I can for the unit with the motor in, any ideas?

 

Thanks

 

Chris

[jpendle]

Z21 and others need to see a motor load to read and program CVs.

Either program both cars at the same time or put the chip from the dummy into the motor car to program it.

Alternatively buy a seperate chip programming gizmo. My brain is dead at the mo but someone else will be able to recommend something

 

Regards,

 

John P

[Yardman]

Put a 100r resistor accross the motor leads in the trailer car. You should then be able to read the CV's and program it.

[RAF96]

Put a 100r resistor accross the motor leads in the trailer car. You should then be able to read the CV's and program it.

Temporarily for programming only

If you have both cars on the same address and apply throttle you will cook the resistor.

The dummy car sound (you don’t say whos) should work without a motor load.

Rob

[Yardman]

Temporarily for programming only

If you have both cars on the same address and apply throttle you will cook the resistor.

The dummy car sound (you don’t say whos) should work without a motor load.

Rob

Not true. Set the trailer car speed table to zero. Easier in Decoder Pro. You do have Decoder Pro, if not why not? Also both decoders should be programmed with their own address, then you can consist them together  and things like the horn lights will work correctly and respond correctly to direction of travel.

[RAF96]

Not true. Set the trailer car speed table to zero. Easier in Decoder Pro. You do have Decoder Pro, if not why not? Also both decoders should be programmed with their own address, then you can consist them together and things like the horn lights will work correctly and respond correctly to direction of travel.

I do have DP and most other such things and very usefull it is too. What I don’t have is two of anything to consist like for like (unless you count my HST TTS pair), much less an 800 to play with.

 

Unfortunately some decoders cannot be adjusted to zero out the throttles as per your advice, hence I stick to the temp resistor if and when required, which isn’t necessary with my main controller.

 

Rob

Edit to add clarity - I hope.

Edited November 18, 2018 by RAFHAAA96

[Yardman]

The problem with using a temporary resistor is you will need to open the vehicle up to re-connect the resistor if you need to reprogram at any point. What type of sound decoders are you using? I assumed it was Loksound or Zimo. Both of which can be set to zero speed. However I'm not sure how a sound decoder will respond if it doesn't have a motor to receive back emf from.

The original question was just how to adjust cv's on a decoder without a motor connected. If you go to the expense of fitting two sound decoders I would have thought it would be worthwhile to use two power cars.

[Oldddudders]

If using a programming track, then I think the resistor needs only to be across the rails. If programming on the layout, then program the two decoders to the same address, and I think the one motor will enable notching up on both decoders. Then place the dummy on the programming track, with resistor, and add 1 to CV29 to get the lights to reverse. I am not sure how to get the horn to operate on the leading car only, unless you can program it also to be direction-dependent.

[Yardman]

A resistor across the track won't work. Programming pulses the motor circuit and the comand station expects a response. The solution to horns, directional lights etc. is to give both decoders different addresses and then consist the two vehicles. Assuming your DCC system supports consisting, all the better ones do. If not it's time to sell your system and buy a propper one. When consisted you operate the consist from the leading cab, whether powered or dummy and the horn will only blow from the leading vehicle and directional lighting will respond correctly, this is the default setting for systems like Lenz, NCE, Digitrax, MRC, etc. With advanced consisting it is the decoder that knows it is in a consist (CV19) and remembers when the power is turned off. it doesn't need to be reprogrammed each time. If in doubt read the manual.

[Nigelcliffe]

Any half-decent decoder can have its functions programmed to be directional.   So that fixes the horns, etc.. regardless of how the loco decoders are addressed.   

 

Running pairs of power cars as a consist is one solution, but not the only solution, nor is it necessarily the "best" solution.  Depends on a lot of factors, including individual preferences. 

 

 

 

And, to make consisting somewhat less simple than Yardman suggests...   When advanced consisting (CV19), there are additional CVs which determine which functions respond to the consist address and which to the loco address (which remains available to operate the remaining functions).  So, in a pure advanced consist, if the horns work from the consist address, then both will sound, if the horns are set to work from the loco address, then they won't sound from the consist address throttle, but will need a second throttle with the engine number active to sound the horn. 

   
The notion of a "lead" loco in a consist is a function of certain command stations consist assistance (regardless of whether they use CV19 or duplicate throttle messages to multiple addresses).  It really does depend how you do it, and with which command station.   You can see this with any of the systems which "assist" by following their manuals for assisted consisting, and compare the results with just setting CV19 manually in two vehicles, and then calling up that short address.  

[Izzy]

 However I'm not sure how a sound decoder will respond if it doesn't have a motor to receive back emf from.

 

I don't know about other makes, but my Zimo & TTS don't need a motor in circuit to work. Obviously they work in response to the throttle along with the inertia settings, but not the actual motor control BEMF responses. Otherwise the sound would alter depending on the motor/gearing used and the current draw.

 

As a consquence I have been able to 'piggyback' TTS decoders onto locos where they can't offer decent enough motor control and use another make (Zimo) for this, so in effect they are just function only decoders, which I believe were how early sound decoders were.

 

Izzy

[Pete the Elaner]

However I'm not sure how a sound decoder will respond if it doesn't have a motor to receive back emf from.

The original question was just how to adjust cv's on a decoder without a motor connected. If you go to the expense of fitting two sound decoders I would have thought it would be worthwhile to use two power cars.

It depends on how the sound project is written in the first place.

 

My (Loksound) HSTs use the same address, but only 1 power car is powered. Horn sounds from whichever car is in the forward direction & both engines are speed dependant.

I later fitted a Zimo to a steam engine. Before fitting, I tested it on my decoder tester. I could not get it to chuff at all. It seemed that its chuff rate depended on motor back emf. I can understand the logic of this because the chuff of a steam engine is entirely proportional to wheel speed, but the same is not true of a diesel, so I would expect diesels do not use EMF feedback for engine sounds.

 

My decoder tester is a MERG kit. It has a resistor across the motor terminals to allow a decoder to respond to CV reads, but this gets hot when you test it for forward & reverse, when the LEDs light up. This is fine for short programming sessions but I would not want to leave it on full power for very long.

 

As for the comment that all speeds an be set to zero in a speed table, this did not work for me. I have several sound fitted class 31s so I wanted to use 1 as a permament dummy in a pair, because this was much easier than speed matching if I never intend to use it powered. I removed the gears then tried to disable the motor, because I wanted to keep this connected so I could read back CVs if I wanted to.

No matter what I did with the speed table, the motor still spun. This is not really a problem because the engine sounds are louder than the motor anyway.

I would use Drivelock to isolate it, but this is not available because the decoder is a v3.5.

[Crosland]

If using a programming track, then I think the resistor needs only to be across the rails.

 

No, that's an old kludge for some poorly designed systems that could not program correctly. It will make no difference to programming a decoder that does not have a motor connected.

[Novco007]

Hi All,

 

I’m amazed that I missed all this, I had asked to be notified immediately when a response occurred!

 

The two cars have loksound chips in.

 

I have played with CV29 and changed both the motor and dummy cars.

 

The motor has it programmed as 15, If I swap it to 14 it runs in the wrong direction, according to the lights, oddly the horns sound when the red lights are on, but it runs forward. Swapping back to 15, it runs forward with white lights and no horns sound.

 

Programming the dummy on a program track with the Z21 maintenance app on a PC, does program the chip, but you get an error reported.

 

I have decided to send it back, from where it came, sort of. I got it from Hattons and they fitted the chips and sound, which I believe is from Olivia’s Trains. Kindly Olivia’s Trains have offered to reprogrammed then, I just have to pay postage, which is fair enough.

 

I also have an HST, fitted with Zimo chips in both cars and this works perfectly, and both cars use the same ID. Video below.