I have a relay board that I want to represent in my schematic, but it is connected by hookup wire in screw terminals. I will have it bolted to my main board using standoffs, but the connections will still be made by hookup wire via terminals on the main board. Is there a standard way to represent such a thing? Thanks!
Typically, a schematic for a PCB does not include direct (part of the netlist) documentation of any off-board connections. So, the way I would represent this is:
- A connector symbol representing the screw terminal block
- A “board only” footprint representing the relay board, showing its 3D model and 2D courtyard / mounting hole locations
- A set of mounting hole symbols/footprints representing the places the standoffs will screw in
- Some text notes next to the connector describing the wiring to the relay board, if desired.
It is quite common to put parts on the schematic that are not on the PCB. Sometimes this is handled with a bit of a dirty trick. For example for a front panel where a potentiometer is directly mounted in the front panel, you can assign a connector footprint to the potentiometer schematic symbol.
This would not work for a multi pin terminal block. For this I would put the terminal block itself on the schematic. You can add the relays themselves to the schematic too, and then you can edit their properties and set the Exclude from board attribute. If you do this, then also make a not on the schematic that these relays are mounted elsewhere, although the terminal block in between also makes that clear.
Another option is to create a separate KiCad project which has the relays (plus terminal blocks?) and use this just for documentation and mounting guide.
I have various sizes of wire-pads defined for soldering external wires. I use them with a W ref-des prefix (though in the past I have seen E prefix).
I also have a variety of symbol-only (no footprint) items that I use for annotating things external to the schematic. Just get creative in the symbol editor.
Perhaps a symbol (with mounting footprint as chris suggested) kinda like this? I use Z for module ref-des – will also be in your bom.
