Electrical installation and pneumatics (DIN-compliant)

Purpose

Ensure operator and bystander safety
Provide deterministic, fail-safe shutdown behavior
Comply with applicable DIN / EN machine safety principles
Keep safety independent from software and firmware

Electrical installation

Electrical system designed in accordance with:
- DIN / EN 60204-1 principles
Separate grounded electrical cabinet
Segregation of:
- mains power
- motor power
- control signals
- sensor signals
Use of:
- main contactors
- appropriate fusing
- protective earth bonding
All safety-relevant wiring implemented in hardware

Emergency stop (E-stop)

Emergency stop system implemented as hardware-only
Normally-open main contactor
E-stop directly interrupts:
- mains power to drives
- control power where required
No software involvement in E-stop behavior
E-stop overrides:
- Duet
- ECU
- Raspberry Pi

Pneumatics

Pneumatic system used for:
- tool clamping
- auxiliary machine functions
Depressurization valve:
- normally open
- wired directly into shutdown circuit
Behavior on:
- E-stop
- power loss
Result:
- automatic venting of pneumatic system
- loss of pressure as safe state
Pneumatic control logic not software-dependent for safety

Fail-safe behavior

Loss of electrical power results in:
- drives de-energized
- pneumatic system depressurized
Safety chain behavior is deterministic and testable
No single software fault can inhibit safe shutdown

Scope limitations

No software-based safety logic
No safety functions implemented in Duet, ECU, or Raspberry Pi
Safety system not affected by firmware updates