pH/ORP stamp using UART port

Paul, thank you very much for your answer.
I have connected the stamp to the Rx/Tx of Arduino and the green led for transmission blinks. I assume somehow serial data is available.

I am not an expert at this (the first time programming for the serial port) so bear with my innocence.

I was under the assumption that the inData cycle will read on bit at a time from the serial device and will store it in this vector. After that I thought that atoi() will convert the char string into a decimal value.
Are all this correct ? Can you please help me understand how to read the ORP from this stamp.

I don't' have the physical ORP probe connected, but the stamp should change the output when the probe pin goes to gnd.

cheers,
Marian