Limit and Stop Switch Circuit

摘要

When things go wrong, it is essential that there be a way to quickly say STOP. Limit switches are used to detect when an axis is at the end of travel. The manual Stop switch lets the operator react quickly. It is common practice to use normally closed micro switches on the limits. They are connected in series so if any switch opens, it is detected. Furthermore, if the wire breaks, it is detected. What is less common is where to feed the signal. You can feed the signal into your breakout board (BOB) and let the software shut off the axis feeds and spindle. But what if you hit a limit because the software went insane? It is far better to use the limit signal to directly turn off the stepping motor drivers and also inform the software of the fault.