Industrial PH-Sensor (S-pH-01A)

i just got this industrial grade ph sensor:

It should be calibratet by factory but i measured some liquids and it seems like it needs a new calibration or it hasnt been calibrated correctly.
I got another sensor with the same probe but another transmitter and other sensors to compare.

Is there another way to calibrate it than with Modbus RS485?
And if not, which software can i use for RS485 communcation?
I use an esp32 board with ads1115 to get the analog input.

You can find the calibration document in the FAQ option here:

However, it says the sensor is factory calibrated. Let’s see what seeedstudio suggests.

okay i undestood the part with the analog output now, but still i dont know how to calibrate.
The recommended modbus programm is not working correct or i cant use it.
Maybe anyone has experience?

Thank you for your inquiry regarding our sensors. We would like to address your concerns and clarify our calibration process.

Please note that our new pH sensors do not require calibration unless the data is found to be offset in the standard solution test. Additionally, our sensors are calibrated before leaving the factory, so you may not need to calibrate them again. However, if you do need to calibrate them, please note that calibration requires the use of a standard solution, and please refer to this link:

Pg 5 of the calibration document mentions downloading the “serial port tool”. Does anyone know where I can find the download link for this software?

Please be advised there are two types of calibration… the sensitivity of the probe itself and how the data is received by the microcontroller

In general you should have three calibration solutions… high low and neutral… you put the probe into the neutral solution and should get an output of 7

Any variation should be corrected out in software my a mapping function of some sort… same with the high and low standards