The optical endstop signal is read from oscilloscope Channel 4.
| Voltage | Meaning | Action |
|---|---|---|
>= 4.5V |
clear | continue |
< 1.0V |
triggered | STOP |
1.0V-4.5V |
fault | STOP |
| unreadable | fault | STOP |
STOP means feed hold has been sent if possible and the current workflow must end. The operator must inspect and explicitly restart.