Scale Speeds and CVs 67 to 94

[Ian_B]

I am accustomed to setting DCC Speed Table CV's using a Sprog as I have locos manufactured by Hornby Dublo; Wrenn; Triang; Heljan; Hornby; Dapol and DJ [Kernow].

When Railmaster is set to Scale Speed with the correct variant of a locomotive entered into the locomotive database is it possible to 'update' the steps in the chips speed table to match these settings or will it simply read the original settings on the chip?

Presumably the 'Scale Speeds for any given loco are based on the fact that Hornby have decided that CV 67 = A mph; CV 68 is B mph etc up to CV 92 = Z; CV 93 AA & CV 94 AB [28 steps].

Does anyone know if there is a chart for each locomotive listing the CV settings Hornby use to achieve these scale speeds?

Regards

 

Ian

 

[Chrissaf]

Hornby RM 'scale speeds' are only pre-configured within the RM database for Hornby branded locos. The 'scale speed' settings used, are contained purely within the RailMaster software. It is the RM software that manipulates the speed and direction DCC commands sent to the decoder to simulate what you are doing manually with the Sprog. Hornby 'scale speed' does not write any values to decoder CVs, nor does it read those existing decoder values back to check against the RM database. So for example, if you take a Hornby loco that responds in a 'scale speed' manner using RM. Then run that same loco from a normal DCC controller, the loco will respond to that non RM controller using the hardware CV settings in the decoder that might still be set at 'factory defaults'.

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Think about it logically. If using RM 'scale speeds' needed to modify decoder CVs. You would get a RM message when creating a new loco in the RM roster asking you to place the loco on the 'Prog' track so that task could be processed. This doesn't happen. You don't even need to have the loco in your possession to set up a new loco in RM. You can set up a new loco in the RM loco roster whilst the loco is still in transit to you in it's box. So that it is ready to run when it arrives (barring changing it's DCC address).

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AFAIK there are no published settings used for locos within the RM database. Mainly I suppose because the information would be of no value to anyone other than Hornby as they are not related or mapped to CV values.

[Ian_B]

Thanks Chris,

A pity they've gone about it that way as it prevents a Hornby loco being calibrated to operate at  scale speeds at all times.

I assume from your reply that if Railmaster is set to 'Scale Speed' the loco will respond to the RM database settings regardless of whether chip is set to the original factory settings or have been altered by the owner.

 

Regards

Ian 

[Chrissaf]

Maybe....I don't know, as I don't really take any notice of 'scale speeds'. I just adjust the throttle manually till I observe what looks right to me as a subjective assessment of speed, motion and distance travelled. My view is "If it looks right....it is right".

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[96RAF]

If you set your speed table to match the RM scale speed table then surely the switch from RM to stand alone controller should be speed seamless.

 

I am sure somone on here exported the speed table CV Values into a spreadsheet and had a way of adjusting the values. There is a clue to the individual value in the string starting 99xx.xx.xx. in the RM CV read-back list. Problem is at next revision RM would probably overwrite that table if you amended it and you would then be back to square one.

 

I stand with Chris on this, RM indicates a shunt and cruise speed for a loco and anything in between is up to me to set.

[Fishmanoz]

Rob, are you suggesting that with scale speeds set, RM keeps a table for each loco containing values that can be exported and applied to CVs outside RM, even though RM itself does not use its table to set CVs?

 

In fact, do we know anything about the sophistication of RM’s scale speeds?  In fact does it do no more than define the correct speed steps for scale shunt and cruise speeds?

[96RAF]

Fishy

It was just my thoughts as to how scale speeds is handled by RM. The blurb says each loco is calibrated so that data must be held somewhere and I presumed it must be the more complex curve rather than the simple three point speed curve given there are also cruise and shunt settings to pick and user adjustable.

 

As Chris said nothing is written to the decoder as there is no CV that handles scale speeds, so it is all held in the mind of RM just like it RM double heading.

 

Based on that I wondered if the scale speed data could be extracted and if written to the complex speed curve then maybe you could match RM scale speed control to manual controller control, as presently there is a definite mismatch between the two.

 

[Chrissaf]

The logical place to hold the data within RM is in the 'resource.mdb' file. But this is just a pure guess.

[96RAF]

I don’t have the time at present to do any research into the whys and wheres of this so I will have to leave it to others - if interested.

[Fishmanoz]

Isn’t resource.mdb blank until you start adding locos to it?  If so, the data must be held elsewhere with the full roster of locos before being added to resource.mdb when a loco is added.

[96RAF]

I have an application called Resource Hacker which allows me to ‘read’ exe, cab, dll and other normally unaccessible files, so given I can find some slack in my schedule I may be able to take a look and see which file is hiding the scale speed data.

[Chrissaf]

Isn’t resource.mdb blank until you start adding locos to it?

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Yes, but I was making the assumption that the relevant scale speed info gets copied from the source data into resource.mdb when you add a loco to keep the relevant data for a loco all together and shorten 'look up' latency time. If the 'scale speeds' database truly holds info for >2,500 Hornby locos, then I would think it is impracticable for RM to look through the main file for the data every time you change speed on a loco being controlled.

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Although, I suppose another theory could be. When RM starts up....it looks at what locos are in the roster. Then goes to extract the 'speed scale' data from the database repository, then copies the data to the PC RAM for quick access during a running session.

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Another theory for it being held in resource.mdb for each loco added to it. What about when you profile a non Hornby loco for scale speed. ie timing a loco running on a 6.274m loop of track and entering the timings in the 'scale speed' box....see page 37 of the RM manual. I can't see that data being stored in the main loco 'scale speed' database, else it would get over-written at the next RM update. RM updates do not over-write resource.mdb

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At the end of the day this is all conjecture as only HRMS truly know how they implement 'scale speed' data.

 

[Fishmanoz]

Not sure you’ve understood me Chris.  I’m not suggesting that RM goes to the original source for the scale speed data each time you run the loco, rather that there is an original source containing the data for every loco somewhere other than resource.mdb which is only copied into resource.mdb when you set up a loco.

[Chrissaf]

Which is precisely what I was suggesting. Both singing from the same hymn sheet.

[Fishmanoz]

Furious agreement then.