~steelexodus

FANUC's FSSB

Posted on 2026-08-26

Keep them motors spinning

Today I am reading up about FANUC's FSSB, which is the physical fibre optic calbes that sit between the CNC controller and the servo amplifiers.

It's quite interesting to think about this, and how to emulate the same setup using Pi Pico's.

The CNC controller does the trajectory calculations, send a packet every single synchronization cycle out to the connected servo amplifiers. These are connected in a daisy chain layout, so all amplifiers see the exact same message.

Thinking about it, the same can essentialy be achieved using the Pico's PIO system, ensuring that timing is kept to a minimum.

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