This project interfaces a Cincinnati Acramatic 850 I/O rack to the Centroid OAK CNC controller. It makes the Acramatic rack appear as a PLC board to OAK. 8 input cards and 8 output cards are supported.

This board is currently (2024) in use on a large (30″ x 80″) Cincinnati 2220U-80 CNC lathe that we retrofitted with Centroid OAK in 2023. It saved us considerable rewiring of the machine I/O, plus the cost of numerous expensive Centroid I/O boards.

This board can also connect several other I/O boards to Centroid:

  • Fanuc 6 “connection unit” (A20B-0008-540) to Centroid OAK
  • Yasnac MX3/LX3 I/O board (JANCD-IO21) to Centroid OAK

Please inquire for more information on those applications.


In early 2022 we built prototype boards for ADD-A850.

This primary purpose was to connect the Acramatic 850 I/O rack backplane onto a synchronous serial link used by the Centroid OAK. It can also implement an asynchronous serial link (RS-485) to connect to our FAR-25 or other controllers. A generic Modbus-485 version to connect to LinuxCNC (without one of our control interfaces) is also possible.

ADD-A850 prototypes with fancy laser-cut sheet metal!

This project uses a more modest microprocessor chip than our control-interface projects (but still a powerful ARM Cortex M4). We bought a reasonable stock of them which we hope will cover foreseeable needs.