Trackplan with LED`s




A MIMIC panel project

Regardless you are running analog or DCC with or without a computer program a MIMIC panel with a track plan and LEDs for various indications is both stylish and practical.  Personally I use a PC for DCC control and have all the information on the PC-screen, but have nevertheless chosen to build a MIMIC panel with LEDs to hang on the wall. The PC-screen images quickly becomes "messy" when the layout is growing and a lot details are displayed.
If a MIMIC panel contains LEDs for occupied blocks, routes, signals, etc., it is easy to come up for over 100 LED `s or more. Traditional cabling which is very extensive and difficult to manage for such panel. An alternative is to use the DCC communication with stationary decoders in the panel to drive the LEDs, but what will this cost? Totally unrealistic from an economic point of view.
A Model railroad organization in England - "MERG" (Model Electronic Railway Group) has developed a solution that is very cost effective where you can transfer a large number of distributed signals just using two wires. Transmit modules installed at the block sensors, various switches, etc. and receivers in the MIMIC panel. All connected by two wires and without amplification the communication signal  works on cable lengths even for club premises.

MERG sells  to non-members but I recommend to become a member of MERG and free to take part of a huge amount of construction tips and finished products in terms of Model railroad electronics. Membership gives free support and access to a large library of Model railroad documentation and a distributed newspaper "MERG Jourmal". A very useful Forum is included.

Panel construction

The trackplan is drawn with the program Corel Designer but could be drawn by any program like MS Paint. Alternatively, you can make a copy from the track image in a Model railroad control program. After som editing the trackplan is printed on a color printer at 180 grams "matte" photo paper used as a front paper. I have chosen to divide the current track plan in 3 sections, each on A4 standard. When printing, each section is fitted so they join together. Holes for the LED`s are made to the photopaper with aholetong of appropriate diameter, depending on the LED size.
The photopaper with trackplan is then put on a 3 mm plexi sheet of A4 size (or any sheet of wood or metal) and markers are done carefully in LED holes on sheet. Then drill with a new, sharp standard drill. Bets if you predrill with a 1 mm drill.
If the hole in the paper and the hole in the backsheet dont match exactely the differens will be covered by the edge of the LED holder.. Do not drill through photopaper and the backsheet simultaneously.

The backside of the photo paper is then  sprayed with "Dana-glue"  and let it dry for 30 minutes. With just one surface glued you will have a temporary bond and the photopapaer can be removed and put back again.  If the front paper with the trackplan is damaged or it is to be modified, it is possible to replace the frontpaper. 
Make a frame made of aluminum L-profile or any type of wooden frame. Corners are fixed and screwed with corner blocks of wood.
The inside of the framework is provided with 1 mm adhesive rubber string. 
The LEDs are soldered  to a connector on the back of the panel or as in my case described below, where the LEDs are connected to communication modules.



 "PTP Lite" communication modules from  MERG 

The English Model railroad organization MERG  has produced a large amount of electronics solutions for model railroading. This includes the "PTP Lite" - communication modules able to transfer a large number of signals on just two wires. This in itself is not unique in any way but what is interesting is the low cost compared with other similar solutions.
PTP Lite consists of 3 basic modules. Transmitter (PEEK), receiver (Poker) and control module (Poller). These modules are identical regarding both hardware and software. Function is determined by a jumper on the boards (transmitter / receiver) and the controller module (Poller) is identified by unique address = 0. The receiver and transmitter module for exchanging data are given the same address.
This means that the data from switches or other sources is placed on the transmitter module inputs and  immediately presented on the receiver outputs. The control module (poller) will see all events on the sending module and mirror thist to the corresponding receiver module over the two wires. 
Each module can transfer 8 data signals. Maximum number of modules is 63 which gives a max  transfer of 504 signals a replacement of a cable including 504 wires +ground.  If more is needed you can build  additional networks of PTP Lite  with a poller in each network . The control module (poller) can be placed arbitrarily along the network. 
The MIMIC panel is just an example of applications of the PTP-Lite system and can be used in any context where you want to transfer many signals on two wires. Additional 2 wires are needed for power supply (+5 V) if power only is available in one end. PTP-Lite is not limited to a point to point service. A multidrop type network  can be built up.





       Receiving modules on the backside of the MIMIC panel                                   Transmit modules attached to the blocksensors
Functional test of PTP Lite 

Before the PTP-Lite modules are finally mounted, it is appropriate to perform a functional test and to program addresses for the modules in a separate set up. The following test card acts both as a function test and address programming device.

Following is just to explain how easy it is to prepare the modules for address and function.



Address programming

Set the address with the DIP switches on the carrier board  (Poller address: 00)
Mount link JP2 on the actual module (besides LED)
-  Place the module to be address programmed in the Peeker pos. 
-  Connect +5V to the carrier board 
-  The LED will light up constantly
-  Remove JP2.
-  The LED will blink 3 times. The programming is finished.
Remove +5V
-  Remove the module
-  Continue with next module

The Poller is defined to be the only module having address = :0
Transmit / receive  modules are programmed to address : 01 3F hex
Peeker / Poker in pairs with same address

Note: Modules mounted in Poker or Poller pos. does not have any effect to the address programming procedure

2.   Function settings

4.   Poller   -  JP1 mounted
Peeker -  JP1
Poker   -  JP
1 mounted

The picture shows the set up for a test procedure for transmitting data from Peeker to Poker controlled by the Poller (left).  Setting the DIP-switches on the carrier board will set the corresponding LED at the Poker pos. on the carrier.


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Per-Ake Jansson, email: