PLC – 4 Module Motherboard

This is the 3D from a 4 module motherboard. I originally planned to use standad 90mm wide boxes, meaning that the motherboard probably needed to be 86 – 88mm wide, but this draft is 91mm wide. It means I will have issues using standard 90mm low cost wide boxes, but 2,5 mm is a lot to cut on each board. The reason for the extra mm is because the motherboard need to leave ca 1 mm between boards otherwise it would be to tight. Board cuts are not that clean or accurate ans 1 mm gap leaves plenty of space for inaccurate fits.

Back to the box issue I am tempted to make my own custom boxes using a 3D printer. I also need some custom cover on the modules and that might cause me to leave extra space for per module, but that is for later. I like my 45 x 25 mm module design, so I hesitate to change it. The issue is that it is easy to remember and if I continue to shrink the board it will leave the format useless. This is actually a very small board as is,

I like the flat-packed, modular design because this allows me to assemble modular systems that is easy to fit on any equipment. The 3D module below show 4 x Ethernet modules mounted since that is the only module I have yet. I have not added headers on the motherboard, but distance between motherboard and module is ca correct. One nice detail here is that adding electronic components on the bottom will shelter them a bit as well. The total width will grow to ca 100mm if I add a box per module. In that case I will have a bottom box for motherboard and a separate top box for each module + dummy for unused slots. That will add 4 mm on each board – 2mm on each side – so the modules would be 49 x 29 on the outside and 100mm wide in total. I need to work on the mechanical design details, but I think this will work out fine. The ethernet module have some extra height due to RJ45 module and it’s headers.

Just adding a differnt view – removed the modules at right and moved in the template module 3D to give a better idea of how a real system might look.

A minor detail here is that I have started to export picture more directly from KiCAD – something that saves me time.

Categories: PLC

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