Re: More from IHMD

[Bill Lohman <844bill@gmail.com>]

Hope the following helps.

 

It is my understanding that the DCS TIU and a Proto 2 Engine use both the center and outside rails to communicate.

 

On page 16 of Barry Broskowitz' 161 page DCS O Gauge Companion, the "almost official" DCS bible, informally indorsed by the MTH DCS development group, it states the following.  

 

"The TIU determines for which PS2 engine the command is intended and sends the data packets through the center rail to the engine.  The engines receives the data packets, sends acknowledgement data packets through the outside rails back to the TIU and executes the command". 

 

Before removing DCS from my layout I convinced myself that two factors negatively influenced day to day DCS operation on my layout.

• 1. Dirty track and dirty engine wheels and pickup rollers -- much more than with TMCC/Legacy.
• 2. Engine batteries that are not fully charged.  If club members take DCS Proto 1 or Proto 2 engines out of storage and bring them to the club layout they run the risk running afoul of this.  The fix is to pre-charge the battery (in the engine on a track or with a charger for engines equipped to accept one) or to replace the battery with a BCR (battery component replacement) device.  The BCR has a capacitor in it that charges up very quickly when track voltage is applies. They are available on Ebay and Internet sellers.

 (Also please note that if one attempts to start up a Proto 1 engine with a weak battery it can lead to the chip being scrambled which can only be fixed by un-scrambling the chip.  This requires a de-scrambling kit which MTH sells in recognition of the problem.  This fortunately is not the case with a Proto 2 engine.  A weak battery will just impact performance until the battery is charged).

 

Suggest whoever is interested in retaining and improving this version of DCS on our layout contact Dave Hikel and pick his brain.  Dave is an accepted industry expert and as you can see from Ricky's initial message above, Dave seems to have vastly improved DCS performance on the Independent Hi-Railers, Midwest Division's huge modular layout by adding multiple TIU's and by using the "Susan Deats" RC circuits which are extensively described, used and discussed on the OGR Forum.  He seems like a very friendly and helpful guy based on his OGR Forum postings. 

 

Bill

 

 

 

 

 

On Sat, Oct 30, 2010 at 3:28 PM, Ira Schneider <ira_schneider@iname.com> wrote:

Scott,

The TMCC/Legacy signal is carried on the outside rails.  The DCS signal is carried on the
center rail.

With the scheme used by IHMD, they isolated the center rails to create blocks, but
not the outside rails.  TMCC/Legacy would still work correctly on their layout.

You can have several TIUs in a layout as long as each TIU channel is connected to
a block.  I don't believe you can have multiple TIUs connected to a single block.
On our layout, we currently have four blocks - one for each of the four mainline tracks.
Each TIU channel is connected to one block.  The connections are done within the
power cart.

As I understand their scheme, they divided their layout into multiple blocks and had
a TIU near each block.  Therefore, each TIU only had to deliver the signal to a
small segment of the layout.  Again, this requires isolating the center rail between
the blocks.  I am not sure how we would be able to do that, since we have three
sources of signals to each module:  the bridge tracks, the module wiring harness,
and the cross layout cables.  They said their layout is a fixed configuration.  Therefore,
they can create blocks wherever they want and they can dictate how the modules
are interconnected and use special isolated bridge tracks and module wiring.
We have a much more fluid layout and trying to create blocks would be much harder.
One way to create blocks on our layout would be to use special bridge tracks with
fiber pins in the middle of the center rails (one set for each block end point).  We
would also have to use speical jumper cables at each block end point.  These
cables would only connect the common and non-track power wires between the
modules.  We would then have to rewire the trailer plug connectors coming into the
corners to route track power through a TIU (one channel per track).  That would give
us four block per track and four TIUs for the layout, one at each corner.  (I don't
think this is a great idea - but it could be made to work.)

Also, I don't believe this scheme would solve our main DCS issue:  the signal is
not getting from the handheld to the TIU when the handheld is far away (i.e. across the room).
If there were multiple TIUs in our layout (for example, a TIU at each corner), the handheld
could probably get a signal to the closest TIU.  However, since that TIU only controls
the modules near it, we might still have a problem controlling a train which is
at the far side of the layout (since the signal might not get to the TIU controlling
that block).  Their scheme could potentially solve the problem that we can communicate
with a TIU but the TIU can't communicate reliably with the train since the signal
degrades so much on our layout.

I have seen a marked improvement of the DCS signal on our layout when we clean the tracks.

I hope this clarifies their use of multiple TIUs on their layout.


Ira



------
TTAT members reflector.