The project of using multiple Raspberry PI to record sensor data and to use it to control relays started in 2018. I now have (5) RPi interconnected running multiple functions. See below the PC boards I am using and the sensors / software in use.

**** In progress

The Universal board is designed to mounts directly on top of the Raspberry PI. It provides the following:

 - Requires a supply voltage input of 12 V (P0)

- Has a 5 V regulator to power the Raspberry PI from 12 V. (PS0)

- Includes (6) I2C port interface via Cat5 cable. (GP01 to GP06)

- Indcludes (2) on-board relay output (P1, P2)

- Includes (2) on-board contact input (P70, P80)

**** This board is in beta testing

The REB board is designed to interface to the Universal RPi Interface board via Cat5. Each board has (4) output relay slot and has (4) multi-use input

****The I2C bus speed of the RPi must reduced to 38400 to function properly

The I2C-IO board is also design to interface with the the Universal RPi Interface board via Cat5. It is design to accept (2) sensor breakout board. The primary design was for a temperature sensor on P2 and an OLED display on P2. It also has (2) GPIO pins from the RPi connected to P4 and P5 witch enable the possibility of an alarm buzzer and a acknowledge button.

The SSR-DC is designed to be mounted on the REB board and the Universal RPi Interface board. It it used to drive DC pumps / light up to 2A