Simple Computer Aided Railway(road?) Modeler
A lot of folks here run Free SCARM or SCARM for track. 2d-3d and premium; simulator. You can build what isn't available and share the files, etc.. It's the most manipulatable code of the lot.
I imagine you could use the line tool for wiring and layer it; toggle it on/off when inconvenient.
Id likely just use a free drawing app to draw over a complete scarm image.
Not tmcc unless you keep up by recreating the actions of it, but there are free circuit apps that run your designed circuits virtually too. you can draw wire very fast on those those though.
Anyrail and Railroadtrax are the other big names. Anyrail has the intuitve GUI and 50pc free version. RRT probably has the best library/graphics and has a simulation.
