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SSeparate Accessory BUS wiring

RAF96

13898 posts


Community Moderator

The original figures are on the PC which is shut down at present.

I will crank it up tomorrow and post a better picture.

I will also rework the article to force the authoring software not to ‘optimise picture for the web’.

Just be aware these relay modules can be slightly different so check the one you buy meets your exact requirements with regard to relay voltage, trigger level logic, ability to power the board and triggering at the correct voltage, ability to cope with DC load, etc. I bought three before I got one that works with R8247 and a CDU after a fashion.

Halton Brat - Running Win 10, 64-bit - RM (Pro-Pack) with Elite as Controller-A, Select as Walkabout and E-Link as Controller-B - Locos are mostly TTS. http://www.halton96th.org.uk/robs_rails.html

Chrissaf

12104 posts


Community Moderator

After some late night email dialogue with Rob to get details. I have put together this information on Rob's behalf to save time.

 

Wiring the R8247 Accessory Decoder side of the Relay board.

 

The best engineering solution in order to make connections between R8247 and relay board is to make up a wiring harness between the R8247 Accessory Decoder and the Relay board using industry standard DuPont 2.54mm Female Housing connectors. The currents on these input pins are very low, so only thin wires are needed which will aid the termination on the DuPont female terminals. Wire of 7/0.2mm size should suffice. The wires are best crimped onto the terminals using very small fine pointed tipped long nose pliers. It is fiddly, but can be done with care and practice. I have done loads myself, as I make extensive use of these DuPont connectors.

 

Two housings are required. A 9 way housing [1*9] for the relay inputs and a 3 way housing [1*3] for the +5 volt DC power supply.

 

These housings and female terminating pins can be purchased here. Be careful if you source the DuPont housings elsewhere, as normally you have to buy the crimp terminals separately. The linked eBay seller includes the crimps in the listing.

 

The harness is made up as per the graphic below.

 

 

The output [relay contacts] side of the relay board are wired up as per the schematic below:

 

Chris........ Making the wood in the trees visible.

menacesco

27 posts

Thank you both very much. That looks very clear. I am nervously looking forward to starting this project. I'll let you know how I get on. Regards. 

Chrissaf

12104 posts


Community Moderator

My original schematic post now updated to reflect the corrections suggested by Rob to me this morning after reviewing my original post I published last night. The original post from last night has been removed and replaced by a new one this morning.

 

The Relays on the board used in the schematic are 5 volt relays not 12 volt. So the +5 volt DC input supply is used. The board in the graphic is the board linked to in the eBay seller link on Page 2 of this thread and the sellers listing states +5 volt DC operation.

 

Chris........ Making the wood in the trees visible.

RAF96

13898 posts


Community Moderator

Thanks to Chris for the amendment.

 

If the relays are 12v on the module then DC-In should be 12v (my relay board and the pictured module have 5v relays). The jumper as stated is removed to separate JD-Vcc and Vcc. Note you then need a three way housing with the centre pin omitted.

 

If the jumper is left on the module DC-In is generated by Vcc of 5v at the trigger header from an external control circuit such as an Arduino or RasPi.

 

Note that all ‘C‘ terminals are connected together inside the R8247 so only one wire is required on the trigger header to Vcc. Although there is a standing positive of 14vDC on the ‘C‘ terminal this is not realised at the relay module until the floating IN1-8 triggers are pulsed from the R8247 to make switched negatives.

Halton Brat - Running Win 10, 64-bit - RM (Pro-Pack) with Elite as Controller-A, Select as Walkabout and E-Link as Controller-B - Locos are mostly TTS. http://www.halton96th.org.uk/robs_rails.html

Chrissaf

12104 posts


Community Moderator

@menacesco.

 

Since the schematics posted last night have been amended since your last post above. Could you please indicate that you have seen and noted the amendments.

 

Thank you.

Chris........ Making the wood in the trees visible.

menacesco

27 posts

Hi Chrissaf,

I've read the post and adjusted my connector order to match the 5volt version which I have. I already have a 5v 0.2amp supply from an old piece if equipment. Is this suitable to power the relay boards.

Chrissaf

12104 posts


Community Moderator

5 volts DC at 0.2 amps [200mA] is more than enough. The relay board is designed to be used with an Arduino or PI programmable processor board with the relay board getting its power from the same 5 volt input used to power the processor. These processor boards are typically powered by a computer USB port, thus the relay board current draw is likely to be measured in the low mA current range.

 

Thank you for replying, I can now stop bumping this thread and let it slip naturally down the rankings.

Chris........ Making the wood in the trees visible.

menacesco

27 posts

Hi Chrissaf,

I have created my first board and wired the R2847 to the relay board, however, I am having difficulty understanding the output side wiring.

I obviously have 2 relays per point - solenoid motor - with 6 connection points and 3 wires coming from the point motor? I cannot work out which connection points the 3 wires - red, green and black - should go to.

Apologies for my ignorance!

Chrissaf

12104 posts


Community Moderator

The black wires from the point motors do not go to the relay board. They are all commoned together and go to the negative side of the CDU output. Only the red and green wires of the point motors go to the relay board. The positive side of the CDU output connects to all the relay contact levers. All point motor wiring should IMO use a minimum 16/0.2mm wire thickness.

 

The drawing below demonstrates the above text.

 

Note for all readers. The colours used in the drawing below relate only to Hornby point motors. PECO use the same three colours, but PECO use Green and not Black as the common return.

 

 

           My drawing above should resolve all outstanding misunderstanding.

Chris........ Making the wood in the trees visible.

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