Where can I find the Rpm counter value?

[FDY-fr]

I am developing a monitoring system for my 2GM20 Yanmar motor (temperature X4, total run time, trip time, RPM,…). This is based on an ESP32 board dev kit C.
Everything works well and I can get all the motor sensors values displayed with Openplotter (RPI 5). I used all the examples to create my own source code. I want to add an e-ink display to the ESP32 that monitors the motor to display the motor parameter “locally”. I have an issue as I am not able to get locally the RPM (or frequency) value that is sent to signalk. Would you know how I could get that value locally so that I can display that value on my local e-ink display?

Thanks in advance for your support. If you need additional info, do not hesitate to ask.