Heljan 89121 DCC compatible Turntable with NCE DCC systems

[westaust55]

Hello all,

 

First post here.

 

In conjunction with a friend here in Australia we are both experiencing a "situation" when using a Heljan 89121 DCC compatible turntable with an NCE PowerPro DCC control system.

Currently I have been in contact with Heljan but on the basis that we are the only two persons reporting the situation, currently Heljan are not intending to investigate too much to resolve in the short term.

 

 

I did mark up the Heljan 89121 turntable manual with some corrections in 2015 and after a delay they have very recently uploaded the amended manual. But NCE DCC system users may this still find the information confusing.

I have now offered to write some notes for Heljan to make available better outline how NCE DCC system users can set up and use their 89121 turntable and they have accepted that offer.

 

In the meantime, I am also seeking to ascertain from others who have both a Heljan 89121 turntable and an NCE PowerPro DCC control system, if they are experiencing the same "situation."

 

In simple terms the Heljan 89121 turntable does work and there are no problems controlling via the Heljan blue box local controller,

but the "situation" a couple of us are experiencing with NCE result in some limitations and need for care on setting up the turntable and other DCC accessory devices.

 

 

The "situation" we are experiencing is as follows:

1. Selecting a Base address from the blue controller box >= 64 finds that the turntable does not respond to any selected DCC accesory addresses (that we have been able to identify)

 

2. Selection a Base address <= 63 (the Heljan default and on a reset is 57) the turntable will respond to some/all of the possible 48 positions.

 

3. For the highest base address numbers the no of positions appears to be limited. For example Based Addr = 63 and the first 4 bridge positions will accessory address of 249 to 252 will respond but higher numbers will no

    At lower numbers eg 57 I have tested up to 10 bridge positions and all worked correctly.

 

4. With a Based address of <= 63, as well as the Heljan turntable responding correctly at the calculated accessory address [((= Base address - 1) x 4) + Bridge position No] where Bridge position is 1 upwards to 48 max)

    it will also respond and travel to the same bridge position with an accessory address in multiples of 256 higher (i.e. 1 x 256 = 256, 2 x 256 =512, etc)

 

   So if the default Base address is 57, the first position is ((57-1) x 4) + 1 = 225 (as per the manual) and the second is 226, etc
   However currently two of us are finding that in addition to 225, the bridge will also travel to position 1 if accessory address 481, 737, etc is selected.  Same with the other programmed bridge positions.

 

  Likewise if the Base address is changes to 16, the first position is ((16-1) x 4) + 1 = 61  and the second is 62, etc and the TT does work at these accessory addresses.

  However  in addition to 61, the bridge will also travel to position 1 if accessory address 317, 573, etc is selected.  Same with the other programmed bridge positions.

 

 

This means that for NCE DCC control system users there is seemingly care needed to select a T/T Base address value and all other DCC accessory devices such that the total repeating range of accessory addresses does not conflict with the other devices - who wants the T/T to rotate when setting a set of points at some other address?

 

The Heljan manual refers specifically to Uhlenbrock / Lenz / ESU DCC controllers.

Heljan has informed me that their T/T does correctly correctly decode the entire (1-2044) accessory address range and they cannot simulate/cause the "situation" a couple of us in Australia currently experience.

 

 

However, I have around a dozen Team Digital SRC-16 and -152 boards with 15 outputs and 8/16 routes (each Output point and Route can be set a unique address) 

currently covering the range 110 to 335 plus I have a few of my own designed and constructed DCC accessory decoders correctly using accessory addressing

from 400 upwards (for many building, platform, street, etc lighting and simple animation control channels).

None of these non NCE accessory decoder seem to have problems or respond to other than programmed addresses under control of the NCE PowerPro DCC control systems.

 

The "situation" is consistent for both of us, even when no locos are operating, which rules out noise, and I have tried such actions as setting the NCE accessory repeats from 4 to 1 without any change.

While designing and constructing my own accessory decoders, I had a loan of an oscilloscope to check DCC bus and other waveforms and all was good.

 

It is my understanding that Lenz and other European manufacturers have an accessory address scheme based on an address up to 511 then 4 pairs of output (511 x 4 = 2044)

whereas the NCE systems use a straight 1 to 2044 accessory address still sent in the/a 3-byte DCC accessory packet.

 

This post is not endeavouring to "knock"/denigrate the Heljan 89121 turntable.

It may well be the the situation is caused by something in the NCE DCC 3-byte accessory packets.

 

The sole purpose of this post is to see if there are other forum members using NCE DCC control systems and a Heljan 89121 turntable who can try a few tests

based on the above above 4 points and see if there is a common theme between the Heljan and NCE systems or whether we in Australia are alone in the "situation" we experience.

 

Hopefully I can find a few more users of these same two products who can advise Yes they have the same "situation", or No their systems work correctly without repeats at 256 address increments, etc.

That information I will then look to passing along to Heljan along with my proposed notes to help NCE DCC control system users.