Disengage Plotter

Every pen plotter run ends the same way: the tool is still touching the paper, and you either reach for the physical button or fiddle with the machine's software. Disengage Plotter is the node that does it for you from inside ComfyUI. One click, no inputs, and your AxiDraw lifts the pen and releases - the code literally runs axicli --mode align, which parks the machine in a safe, hands-on state.

You'll rarely use it as a standalone step, and that's the point. PlotSVG in this same pack calls the same disengage routine automatically whenever a plot finishes, and so does ComfyUI's interrupt handler - the pack wraps interrupt_current_processing so that hitting Cancel also sends the pen home. That means Disengage Plotter is mostly for the moments the automation doesn't cover: you've queued a run, something failed mid-plot, or you just want the machine released before you swap a pen or move the page.

How it works

It's a subprocess wrapper, nothing more. The node shells out to axicli --mode align and waits for it to return. AxiDraw's "align" mode disengages the drive - pen lifts, motors release - which is exactly the safe state you want before touching the carriage. The node reports back with a status string ("Plotter disengaged successfully." or an error), so you can wire it into a chain and read what happened.

Two things worth knowing. First, this requires the AxiDraw software installed and axicli on your PATH. If you only installed the Python API and skipped the command-line tool, you'll get a clear "axicli command not found" message instead of a plotter release. Second, the node is marked as an output node with no inputs, so it's a dead end in the graph - it does its job, prints a status, and stops.

Install

It ships in the ComfyUI PenPlotter pack. Either use ComfyUI Manager (search "ComfyUI PenPlotter") or:

cd ComfyUI/custom_nodes
git clone https://github.com/wouterverweirder/comfyui-penplotter

Then restart ComfyUI. The pack pulls in numpy>=2.3.4, opencv-python, numba, vpype, websockets, requests, qrcode[pil] and the AxiDraw API (installed from a URL zip, so you need internet at install time). If you only care about this node and not the plotter nodes, that's a fair amount of machinery for a "lift the pen" button - but you won't be running this pack without a plotter anyway.

Common issues

• "axicli command not found" - the AxiDraw software's command-line tool isn't on your PATH. Install the full AxiDraw software and add it, or point PATH at it.
• Nothing happens - the machine isn't connected or the port is in use. The pack can't do much about hardware state; check your USB connection.
• Plotter doesn't disengage after a cancelled run - the interrupt hook is a best-effort convenience, not a guarantee. If your pen is still down, run Disengage Plotter manually.

It's the least glamorous node in the pack and the one you'll be quietly grateful for at the end of a long plot.