Code to control inexpensive USB relay boards to show the state of a Prusa Mini 3D Printer via an Andon (stack light).
The relay-control-code was original forked from Pavel-A's usb-relay-hid library; I maintain a fork of that library which I've made more object-oriented and Pythonic. See that library for more details on intended USB relay-board targets, but in short: most of the "Programmable USB Relay" products from online vendors seem to be the same generic type. They often have a red silkmask on the PCB and blue relays from "SONGLE" (sometimes no-vender). They come in 5V, 12V, and 24V relay voltages.
There are a variety of cheap Andons available from online vendors these days. I hesitate to call them "stack lights" since most of them donts actually stack - rather, they are a single internal PCB with multiple levels of SMD LEDs, which a multicolor plastic shell that slides over them to provide color indication. However, if you're looking for these online, seaching "stack lights" on online vendor sites is the way to go.
You may wish to think about your control voltage vs. your Andon voltage when purchasing a USB Relay Board and an Andon - having them be the same voltage simplifies power supply wiring, though this is not required.
