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Pendolino Alstom DDC Decoders


nevermore

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ok so im getting into the DCC thing & it can be pretty confusing to a newbie

Im looking at adding a sound decoder to the power unit of the alstom & just getting a basic decoder for the rear non powered unit for lights.

How do you programme the decoders so the front & rear units works under one address ?

I dont want to buy a paired set of sound decoders as they would be £220 would probably get the sapphire or the R8249 for rear unit.

any help much appreciated

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The R8249 is perfectly adequate for the dummy car.  Sapphire would be OTT imho.

 

To program them to the same address put the powered car and the dummy car on the programming track at the same time.  Both units should accept the same address.  Get the dummy car set up first, ignoring the powered car.  Then remove the dummy car and make any adjustments needed to the powered car.

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Just to add my tuppence worth to Rog's advice.

 

From interest what controller do you have as some are limited in extent as to what they can program but mostly every controller can at least change a basic address.

 

The reason for doing both at once is most controllers need to see a load from a motor before they can program a dummy decoder, hence fooling the system is possible by having both on track at once, then as Rog says you can do any extra fiddling with the power car after the dummy is addressed.

Rob

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Just to add my tuppence worth to Rog's advice.

 

From interest what controller do you have as some are limited in extent as to what they can program but mostly every controller can at least change a basic address.

 

The reason for doing both at once is most controllers need to see a load from a motor before they can program a dummy decoder, hence fooling the system is possible by having both on track at once, then as Rog says you can do any extra fiddling with the power car after the dummy is addressed.

Rob

Hey rob i will be using the ez dynamis controller for this

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Rob, not sure it's the controller that can't handle programming without a motor load, though it was a decoder limitation.  Not sure how the controller could even tell if there is a motor when the loco is stationery, and only indirectly via current drawn when moving?

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@fishy

According to NMRA when programming the decoder can send a pulse of current to the motor which the controller 'sees' and accepts as an acknowledgement of its enquiry or instruction to the decoder.

 

I had been trying to plot this pulse on the 'scope but had to send the current clamp back which I had on loan, so I'm looking at another way to show it on screen.

Rob

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Hang on, on second thoughts - given the motor connections must be isolated from the track input, how can the controller see a pulse sent to the motor?

 

This quote from the Standards:

D: Decoder Acknowledgment Mechanism

Service Mode operations provide for an acknowledgment mechanism from the decoder to the command station/programmer.  Acknowledgment refers to the ability of the Digital Decoder to respond to a Service Mode instruction issued by a Programmer. Service Mode instructions can be executed regardless of whether or not the acknowledgment mechanism is detected by the command station/programmer. 

Two Acknowledgment mechanisms are available:

-Basic Acknowledgment

-Advanced Acknowledgment

Digital Decoders may provide either form of acknowledgment.

 

Basic Acknowledgment Basic acknowledgment is defined by the Digital Decoder providing an increased load (positive-delta) on the programming track of at least 60 mA for 6 ms +/-1 ms. 

It is permissible to provide this increased load by applying power to the motor or other similar device controlled by the Digital Decoder.

Advanced Acknowledgment See-S-9.3.1 (discontinued) and S-9.3.2 (which really gets down in the weeds).

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