wvmarle thanks for your help. Do you know a DAC module that is compatible with my needs ?
As I understood first I will need to scale my digital variable into a analogic signal. Let's say variable = 7 will output 0 V. Then I need to calibrate my microprocessorB and tell him 0 v corresponds to a pH 7 and also calibrate with another voltage and pH reading.
Doing that my microprocessorB will be able to display the Arduino variable like a conventional pH reading but in reality is other parameter that was calculated.
Arduino --> DAC---> analogic signal ---> MicroprocessorB