Layout Strategies

[tshead]

Thanks for Schemdraw! After trying and discarding a bunch of electrical design GUIs, a code based approach for generating schematics was a real breath of fresh air. I will say that the turtle based approach to layout starts to break-down once you go beyond two-lead components - for the following diagram (rewiring a milling machine for single phase power), I ended-up adding all of the components, then making connections after the fact instead. Curious if I missed anything that could simplify the code?

with schemdraw.Drawing(canvas="svg") as drawing:
    drawing.config(font="Helvetica")

    # Draw the plug.
    plug = NEMAConnector(plug=True).scale(0.66)

    # Draw the circuit breaker.
    cba = schemdraw.elements.Breaker().color("black").length(2).at((1, 2)).hold()
    cbb = schemdraw.elements.Breaker().color("red").length(2).at((1, 1.4)).hold()

    # Draw the stop button.
    stop = schemdraw.elements.switches.Button(nc=True).label("Stop", loc="bottom").length(2).at((1, -0.4))
    
    # Draw the relay.
    relay = GeneralRelay(poles=4).anchor("l1").at(cba.end, 2, 0).hold()

    # Draw the start button.
    start = schemdraw.elements.switches.Button(nc=False).label("Start", loc="bottom").length(2).at(relay.a1, 0, -1)
    
    # Draw the EMI filter.
    emi = schemdraw.elements.Ic(pins=[
        schemdraw.elements.IcPin(side="left", name="GND", anchorname="ground"),
        schemdraw.elements.IcPin(side="left", name="2", anchorname="t2"),
        schemdraw.elements.IcPin(side="left", name="1", anchorname="t1"),
        schemdraw.elements.IcPin(side="right", name="GND", anchorname="ground2"),
        schemdraw.elements.IcPin(side="right", name="4", anchorname="t4"),
        schemdraw.elements.IcPin(side="right", name="3", anchorname="t3"),
    ]).label("EMI Filter\n30A").side("left", label_size=10).side("right", label_size=10).anchor("t1").at(relay.t1, 2, 0)

    # Draw the VFD.
    vfd = schemdraw.elements.Ic(pins=[
        schemdraw.elements.IcPin(side="left", name="S2", anchorname="s2"),
        schemdraw.elements.IcPin(side="left", name="S1", anchorname="s1"),
        schemdraw.elements.IcPin(side="left", name="COM", anchorname="com"),
        schemdraw.elements.IcPin(side="left", name="GND", anchorname="gnd"),
        schemdraw.elements.IcPin(side="left", name="L3", anchorname="l3"),
        schemdraw.elements.IcPin(side="left", name="L1", anchorname="l1"),
        schemdraw.elements.IcPin(side="right", name="GND", anchorname="gnd2"),
        schemdraw.elements.IcPin(side="right", name="T3", anchorname="t3"),
        schemdraw.elements.IcPin(side="right", name="T2", anchorname="t2"),
        schemdraw.elements.IcPin(side="right", name="T1", anchorname="t1"),
    ]).label("VFD").side("left", label_size=10).side("right", label_size=10).anchor("l1").at(emi.t3, 3, 0)
    
    # Draw the motor.
    motor = ACThreePhaseMotor().anchor("t2").at(vfd.t2, 2, 0)

    # Wire the plug to the circuit breaker.
    schemdraw.elements.lines.Wire("|-").color("black").at(plug.a).to(cba.start)
    schemdraw.elements.lines.Wire("|-").color("red").at(plug.b).to(cbb.start)

    # Wire the plug to the stop button and the relay.
    schemdraw.elements.lines.Line().color("lightgray").at(plug.neutral).down().length(1)
    schemdraw.elements.lines.Wire("-|").color("lightgray").to(stop.start)
    schemdraw.elements.Dot().color("lightgray")
    schemdraw.elements.lines.Wire("|-").color("lightgray").to(relay.l3)

    # Wire the plug to the EMI filter.
    schemdraw.elements.lines.Line().color("green").at(plug.ground).up().length(1)
    schemdraw.elements.lines.Line().color("green").left().length(1)
    schemdraw.elements.lines.Line().color("green").down().length(4)
    schemdraw.elements.lines.Wire("c", k=10).color("green").to(emi.ground)
    
    # Wire the circuit breaker to the relay.
    schemdraw.elements.lines.Wire().color("black").at(cba.end).to(relay.l1)
    schemdraw.elements.lines.Line().color("red").at(cbb.end).right().length(1)
    schemdraw.elements.Dot().color("red")
    schemdraw.elements.lines.Wire().color("red").to(relay.l2).hold()
    schemdraw.elements.lines.Line().color("red").down().length(1.2)
    dot = schemdraw.elements.Dot().color("red")
    schemdraw.elements.lines.Line().color("red").to(relay.l4).hold()

    # Wire the circuit breaker to the start button.
    schemdraw.elements.lines.Wire("|-").color("red").to(start.start)

    # Wire the relay solenoid to the start button and the auxiliary contact for latching.
    schemdraw.elements.lines.Line().color("red").length(1).at(relay.a2)
    schemdraw.elements.Dot().color("red")
    schemdraw.elements.lines.Wire("|-").color("red").to(relay.t4).hold()
    schemdraw.elements.lines.Wire("|-").color("red").to(start.end)
    
    # Wire the stop switch to the relay.
    schemdraw.elements.lines.Wire().color("lightgray").at(stop.end).to(relay.a1)
    
    # Wire the relay to the EMI filter.
    schemdraw.elements.lines.Wire().color("black").at(relay.t1).to(emi.t1)
    schemdraw.elements.lines.Wire().color("red").at(relay.t2).to(emi.t2)
    
    # Wire the EMI filter to the VFD.
    schemdraw.elements.lines.Wire().color("black").at(emi.t3).to(vfd.l1)
    schemdraw.elements.lines.Wire().color("red").at(emi.t4).to(vfd.l3)
    schemdraw.elements.lines.Wire().color("green").at(emi.ground2).to(vfd.gnd)

    # Wire the VFD fwd / reverse switch.
    schemdraw.elements.lines.Line().at(vfd.com).left().length(2)
    schemdraw.elements.lines.Line().down()
    switch = schemdraw.elements.switches.SwitchRotary(n=3, arrowcontact=1).right().label("REV", "T1", fontsize=10, ofst=(0, -0.2)).label("FWD", "T3", fontsize=10, ofst=(0.5, 0)).label("OFF", "T2", fontsize=10, ofst=(0.2, 0.05))
    schemdraw.elements.lines.Wire("|-").at(switch.T3).to(vfd.s1)
    schemdraw.elements.lines.Wire("c").at(switch.T1).to(vfd.s2)
    
    # Wire the VFD to the motor.
    schemdraw.elements.lines.Wire().color("black").at(vfd.t1).to(motor.t1)
    schemdraw.elements.lines.Wire().color("red").at(vfd.t2).to(motor.t2)
    schemdraw.elements.lines.Wire().color("lightgray").at(vfd.t3).to(motor.t3)
    schemdraw.elements.lines.Wire("-|").color("green").at(vfd.gnd2).to(motor.ground)

    drawing.save("schematic.svg")

[cdelker]

Yes, it can get messy with more complicated schematics like this one - I don't think you're missing anything. Maybe it's worth thinking about new methods that could simplify, such as something to wire lots of components together at once in a single function call, like this:

schemdraw.elements.connect_all(
    (plug.a, cba.start, '|-'),
    (cba.end, relay.l1),
    (relay.t1, emi.t1)
).color('black')

I'm open to other suggestions too.

[tshead]

Thanks for looking it over - glad I didn’t overlook anything obvious.

The trickiest / least satisfying part so far has been the combination of complex wiring layouts and dots. I’m already of a mind to stop treating the dots as part of the wiring, and start treating them as named junctions that get created with the other discrete components. Then, all of the wiring becomes (relatively) simple.

I think what I’d find most useful is to have API to allow one wire to be created in one statement, no matter how complex the routing, almost like an SVG <path>:

# Wire the plug to the EMI filter (replaces four statements with one)
schemdraw.elements.lines.Wire().color("green").at(plug.ground).to(emi.ground).route("up 1 left 1 down 4 c 10") 

Would you be interested in some of my new elements like NEMAConnector and ACThreePhaseMotor? I’m not wedded to the names.