CAN-Bus Shield OBD 2 Message

I was wondering if anyone have any examples of using the CAN-Bus Shield to do OBD 2 PID request? Let’s say I want to find out the RPM I don’t fully get how I need to send and receive the RPM through OBD PID base on Wikipedia’s OBD-II PID page

I had write one years ago, please refer to … BD_RECIPLE