Reverse Engineering Industrial Inkjet Driver Board (Lattice FPGA + RS485)

[Criminal_Bull]

Hi everyone,

I'm trying to reverse engineer an industrial inkjet driver board salvaged from an 3D printer to build a test rig for Spectra SE-128 AA printheads.

Hardware Details:

Main Board:
- Label: "Spectra_IF_DRV_RS485_12 22486 V004"
- Main IC: Lattice LCMX03L-4300C FPGA (MachXO3L series)
- 4× DIP switches (Switch #3 is ON, others OFF)
- Board connects to 2× adapter boards via 68-pin IDC connectors
- Each adapter board ("Spectra_adapt_Z._12 V01 22485") holds 10× Spectra SE-128 AA printheads

Connectors on main board (top side):
- 1× 20-pin connector
- 1× 26-pin connector 
- 1× 12-pin connector
- 1× 8-pin connector

Connectors on main board (bottom side):
- 1× 68-pin IDC (female) → to printhead adapter boards

What I'm missing:
- Original "driver board" (connects controller to this board via fiber optic)
- That board presumably converted fiber optic → RS485 + power

My Goal:
Direct control via RS485 from PC (USB-RS485 adapter) to replace the missing fiber-optic interface board.

Questions:

1. Which connector is power supply? (Expecting 24V DC based on similar industrial systems)
2. Which connector carries RS485 signals? (A, B, GND)
3. Any guesses on DIP switch function? (Baudrate? Address? Termination?)
4. Has anyone worked with Spectra boards before?

What I have:
- USB-to-RS485 adapter
- Multimeter
- The boards + 20× Spectra printheads

What I need:
- Identify power pins (before I accidentally fry the FPGA!)
- Locate RS485 A/B pins
- Understand basic protocol (or at least establish communication)

I can provide detailed photos if that helps. Any guidance on safe reverse engineering approach would be greatly appreciated!

Thanks in advance!