dren-dk edited this page Oct 15, 2011 · 1 revision

##Safety watchdog##

The machine will need an interlock tied into the lid and e-stop, but some things are harder to detect via a simple switch, those are the things the watchdog routine monitors:

  • Stepper clock to yank interlock if all steppers stop and the laser is firing (g-code crash)
  • If the laser is on and we hit an end stop then the g-code has malfunctioned.
  • Cooling water flow, stop if it's too low.
  • Cooling water temperature, stop if too high.
  • Exhaust air flow, stop if too low.
  • Assist air pressure, stop if too low.
  • Tube Voltage
  • Tube Current

In addition the watchdog will also monitor the E-stop and the lid switches to be able to tell the user why we're stopping.

As an extra shutdown measure the watchdog will also control a mirror that can be moved into the beam to deflect the beam into a large metal plate, in case the PSU fails on, the same mirror will also engage the red aiming laser.

##Other supervisory duties##

The gcode interpreter will only control the motors and the laser, all other controls in the machine will be handled by the auxiliary MCU, such as:

  • Reporting of all inputs to the controlling machine
  • Exhaust relay
  • Assist air relay
  • Cooling fan (PWM 24 V)
  • Cooling pump (PWM 24 V)
  • Cutting chamber lights
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