Main board (Hauptboard) of the digital Festo valve control for the Lesker gas box.

• 24 V input (J201) with T4A fuse, SS54 reverse-polarity diode, SMBJ30CA TVS, 100 uF buffer
• Safety chain input (J202) with LEDs for 24 V and chain OK
• RS-485 from the Raspberry Pi (USB-RS485 adapter) on J206
• One 6-pin bus connector per valve board: J204 = Board A, J207 = Board B

Related boards: Ventilsteuerung Board A (16 outputs), Ventilsteuerung Board B (32 outputs). Status: layout routed, not yet built or tested.