Emulate a PT 100 daughter board with an Arduino

[CNCModeller]

Hi All,
I need to be able to send temperature data and heater pwm over a wireless connection to fit a heated bed to my polar printer. My plan is to use a Bluetooth
connection between two Arduinos. The bed is 240v AC powered via a slip ring mounted in the axel of the bed, and controlled via an SSR. To date it's been controlled by a standalone pwm controller.

The Arduino master on the duet main board side would take in bed heater pwm and pass it to the slave on the bed, and push temperature data back into the duet through the pt100 port.

The slave would drive the SSR in line with pwm demand and measure bed temperature and send it to the master.

That being the case, does anyone know what the protocol for the pt100 board is so I can emulate it with my Arduino. Any thoughts would be much appreciated.

If there is any other way to push temperature data from an Arduino into a D3 mini for heated bed control feedback I'd welcome any suggestions.

All the best.
Barry M

[T3P3Tony]

@cncmodeller the sensor on a pt100 is a MAX31865 so the information on how the duet reads in is in the datasheet.

https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf

Controlling an AC heater over Bluetooth would make me think carefully about secondary safety for overheating or loss of connection.

[CNCModeller]

@t3p3tony said in Emulate a PT 100 daughter board with an Arduino:

@cncmodeller the sensor on a pt100 is a MAX31865 so the information on how the duet reads in is in the datasheet.

https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf

Controlling an AC heater over Bluetooth would make me think carefully about secondary safety for overheating or loss of connection.

Thanks @T3P3Tony, yes I'm going to include a physical thermal fuse on the bed and watchdogs in the code. Totally agree it's a little sketchy unless you think very carefully about not setting fire to the workshop!