Loco CV settings all display 255 as a value

[KPJunk]

I have just bought a 2nd hand Virgin Pendalino (R1076) and have tried to view the cv settings to find the loco ID number .

Unfortunately the first 10 CV readings through railmaster display the value of 255 .

The status / string for the cv value is 

CV1    99 20 1 255 137

CV2    99 20 2 255 138

CV3    99 20 3 255 139

etc

Has anyone got any thoughts on this ?

I thought I would replace the decoder but am wondering if the decoder is an old one as the pins are flat ? Could the decoder and socket be an old style - hope that makes sense

Any help or suggestions  would be greatly appreciated otherwise I may have to consider returning it.

Keith  

[Rog RJ]

The code 255 usually means the software can't "see" a decoder, often due to dirty track or wheels or occasionally because there is no decoder fitted.

 

Try a good clean of the wheels and programming track.  Sometimes pressing down on the loco helps make a good contact with the rails.

 

 

[Chrissaf]

I have seen instances where my loco decoders return all 255 values when being read. I found if I disconnected the main track output of my controller from the track so that ONLY my programming track was connected. The loco CV values then read correctly.

[96RAF]

Just reset the decoder to default address 3 if your controller supports that or re-address it (cv1) to your chosen address.

you don't need to know its current address to progress

[Fishmanoz]

I'm assuming you are using Rm as you've posted to this forum.  Therefore you can write 8 to CV8 to reset the decoder if you wish, or just write any ID you want to the loco.

 

But reading 255 on all CVs almost definitely means you cannot in fact read anything at present, so likely will not be able to write either.  I would be taking both Rog's and Chris's advice to fix that first.

[beejack]

I had the same issue with my DCC fitted Pendolino.  I put it down to the 6 pin chip hornby used.  I couldn't read any CV's in Railmaster using the E-link . Only the Select controller would let me change the address or acceleration/braking values. The Elite had the same issue as the Elink/Railmaster in only showing the values as 255 when read.   I even cleaned the wheels and track expecting that to be the issue but it made no difference.

I swapped out the circuit boards and fitted DCC ready versions with 8 pin sockets. Fitted a non hornby chip and straight away could read all the CV values properly and was also able to read and change far more cv's than on the hornby chip.  

[Chrissaf]

Just to add to my earlier reply and put more meat on the bone. When I have had this issue happen to me, that is reading CV's returns all 255 values. I found I could write without issue to the loco decoder even with the main track output still connected to the controller. It was only the read function that was affected, and as I said, my workaround that worked for me was to disconnect the main track output and leave ONLY the programming track connected during the read process.

[HornbyRailMasterSupport]

Although problems associated with reading and writing CVs are very rare we tend to find that the most common problem is poor contacts.  When code 255 is returned this means that the DCC controller cannot see the loco decoder chip at all.  This means either dirty track, dirty wheels or dirty pick-ups to the wheels.  Another thing that we have found is that if you use a Hornby track power clip or Hornby power track you need to ensure it the digital kind.  There are two versions (digital and analogue), which unfortunately look virtually identical.  The analogue version has a small capacitor connected across the pins.  Just remove the plastic cover on either the track power clip or power track and if you see this capacitor you can just snip it out.  The capacitor interferes with the DCC programming signal.

Two other things that can cause poor reading/writing of CVs is poor cable connections and something on the main layout intefering with the DCC controller's electronics.

You would be surprised the number of people who swear until they are blue in the face that the cable connections from the PROG output of their DCC controller to the programming track are correct, when in fact the metal of the wire is not making contact with the metal of the power clip.  It is easy to insert the cable too far into the connections and thus clip over the plastic sheathing of the cable, so making no contact at all.  Double-check this.

In very rare cases, as alluded to in an earlier post above, the main layout can cause problems.  Sometimes there can be a very mild short circuit occurring on the main layout connected to the TRACK output.  This short circut is so mild that it doesn't cause the DCC controller to produce an error condition, however, it can cause problems with reading and writing CVs on the PROG output, so if in doubt, disconnect the TRACK cable.

The above pretty much accounts for 100% of CV reading/writing problems that we come across.

 

[Yelrow]

Does it also mean, that no chip exists. john

[96RAF]

I have had it where RM doesn't recognise the decoder for what it is for whatever reason e.g. a known Hornby decoder (as that's all I have), when it will then carry on reading into what I presume is a generic list of NMRA cvs based on the presume manufacturers ID found, as opposed to say a Sapphire or TTS cv list.

On such occasion a retry has even produced yet another manufacturers ID.

 

note to HRMS - rm does not currently read cv158 (greyed out) whereas an elite will read this cv, which holds the TTS specific loco type ID code, e.g. Tornado, CotN, etc. Any chance this could enabled please.

[St1ngr4y]

I may be wrong, but aren't there some chips whose cv's can't be accessed if there is no motor connected to the decoder i.e. no load over the output? So you can't, for example, take a new decoder from its packet, and connect it only to the Programming outputs of the controller, hoping to program it before installing it into a loco.

Ray

[96RAF]

Correct Ray

I built a decodertest  rig for 'doing' decoders on the bench, which is essentially a decoder socket, 4 leds (white/red/green/amber) and associated resistors on a bit of stripboard with an old motor/gearbox attached for the load.

 

The motor is marked to show the correct forward direction when normal direction is configured and the leds cater for F0 - direction lights (white and red leds), F1 (green) and F2 (amber) functions.

 

This allows me to a) program, then check that a decoder is working, b) check that the functions are operating correctly and c) check the motor direction accords with settings.

[St1ngr4y]

So Keith's problem could be with the motor or the connections between the decoder and the motor?

Ray

[96RAF]

Again correct Ray there is that possibility.

Until we know more, e.g. does the motor respond to commands, if he could get it to listen.

[KPJunk]

Hi everyone, firstly , thanks everyone for all the input so far .

 Just to confirm from the various suggestions :  

All my decoder programming is done on a hornby rolling road via an SPDT switch which to date has never failed on about 25 locos ( just tested on another loco to confirm)   

Programming track / hornby rolling road are clean  

Loco wheels are clean   

I have an Elite controller and a X9719 flat old style decoder is fitted   

I have tried resetting to default of 003 ,   

I have also tried on the main track Loco ID numbers 390 (Class No ) , 012 ( Loco running no ) in case the decoder was set to either of these.  

Could be a loose wire somewhere which I can usually spot under mag glass and light but all appears ok  -   

Motor and wheels run if I apply a 9v battery momentarily .   

I am running out of ideas so I have just emailed the seller to see if he will try to get it running at the next show that I see him at which is in a few weeks time .   Keith 

 

[Chrissaf]

Have you tried disconnecting your main track connections as HRMS and I suggested in earlier posts?

[96RAF]

Try programming in Paged mode KP as recently I have seen read back of certain cv values corrupt in Direct mode but correct in Paged mode, something to do with how the elite goes about reading stuff.

 

You could also amend cv1 in Operations mode on the main, having removed all other locos first.  the book says you can't readdress when POM but I found it works writing to the cv as opposed to doing an address write in the elite menu.

 

 I do this if I need to address a decoder in Uk as my Elite there has no Prog output, but works fine otherwise.

[withinreason]

I am having a similar problem. I thought at first that this was a track cleaning issue, so cleaned the track thoroughly. I can read the CV's of my existing engines without issue, but cannot read the values of two new LokSound v4 decoders that I have fitted to two brand new DCC ready engines. I hadn’t cleaned the wheels on these as they were brand new straight out of the box.

I have checked that the 8 pin plug is inserted the correct way, I use a separate programming track with a DCC power connector. What else can I check? This is my first time adding my own decoders and I have gone straight to sound, probably should have started smaller!

Any help or suggestions would be gratefully received. Thank you.

[St1ngr4y]

Each new decoder should have a default address of 0003. Have you tried running the loco(s) on your layout using address 0003?

Ray

[Chrissaf]

I too have Loksound V4 decoders. I have found in the past these are difficult to read reliably. I have in the past found that the only way I could read the Loksound V4 was to make sure that my track was disconnected from the Elite track output (in other words ONLY the programming track attached). I use RM for CV reading / writing with my Elite.

.

I too went through all the normal things we suggest, cleaning the prog track rails, cleaning the wheels, applying pressure to the loco etc. The one thing I had always overlooked was to clean the wires that push into my Elite prog track spring terminals.

.

For reasons I won't digress into. I had occasion to remove a small amount of tarnishing that had built up on the prog track wires, by scrubbing them with a piece of 'wet n dry' paper. This removed the tarnishing, and made the wires shiny again with a hint of copper showing through.

.

Plugged them back into my Elite prog track output and my reading Loksound V4 issues were resolved.

.

Can't say that this will work for you, but it did for me. As HRMS said in an earlier reply in this thread. Most reading issues are attributable to poor connections in the prog track electrical path. The prog power output from the DCC controller is very low and will be affected by the slightest bit of dirt or grime. With no appreciable power output, the low current is unlikely to burn its way through a dirty connection. One difference between the Loksound and NON sound decoders, is that the sound decoders in general need a bit more programming power than normal decoders. The additional sound circuitry on the decoder needs charging up as part of the CV reading process.

[withinreason]

Each new decoder should have a default address of 0003. Have you tried running the loco(s) on your layout using address 0003?

Ray 

I will give that a try thank you.

[withinreason]

I too have Loksound V4 decoders. I have found in the past these are difficult to read reliably. I have in the past found that the only way I could read the Loksound V4 was to make sure that my track was disconnected from the Elite track output (in other words ONLY the programming track attached). I use RM for CV reading / writing with my Elite.

.

I too went through all the normal things we suggest, cleaning the prog track rails, cleaning the wheels, applying pressure to the loco etc. The one thing I had always overlooked was to clean the wires that push into my Elite prog track spring terminals.

.

For reasons I won't digress into. I had occasion to remove a small amount of tarnishing that had built up on the prog track wires, by scrubbing them with a piece of 'wet n dry' paper. This removed the tarnishing, and made the wires shiny again with a hint of copper showing through.

.

Plugged them back into my Elite prog track output and my reading Loksound V4 issues were resolved.

.

Can't say that this will work for you, but it did for me. As HRMS said in an earlier reply in this thread. Most reading issues are attributable to poor connections in the prog track electrical path. The prog power output from the DCC controller is very low and will be affected by the slightest bit of dirt or grime. With no appreciable power output, the low current is unlikely to burn its way through a dirty connection. One difference between the Loksound and NON sound decoders, is that the sound decoders in general need a bit more programming power than normal decoders. The additional sound circuitry on the decoder needs charging up as part of the CV reading process.

 

Thanks for the advice. I had just recently tinned or soldered the ends of the wires as they were becoming a little frayed, but I may just replace them altogether with new wires soldered straight away. 

What wire size would you recommend? 

 

[Chrissaf]

I use 24/0.2mm wire, but anything of reasonable size and flexible will do.

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I'll just take the opportunity to point out purely for information that the 'White Arrow in the Blue Box' is NOT a 'Reply to this Post' button. The regular contributors on here would prefer it if reply posts were written in the 'Reply' text box located at the bottom of the page and the Green 'Reply' button used. The reason for this, is that the replies are easier to read if not embedded inside the yellow 'quoted' text box. The blue button is used for quotes and usually not necessary.

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This reply was written in the 'Reply' text box and see how much easier it is to read.

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If you want to highlight or quote something. You just highlight it in the text box and click the 66 quote marks (third icon in from the left at top of box). Then you get the yellow box effect that this paragraph of text is showing as.

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[RDS]

... The regular contributors on here would prefer it if ...

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..... the blue button was removed altogether!