I need your help, friends.
I use PixHawk 2.4.8 with last stable software and I need to receive RPM data from the autopilot side to the MissionPlanner (as I anderstend it can be analogue signal from the pin)
As I seen at the PixHawk firmware configuration via Mission Planner I can not receive data from the PIN as it was for APM (I can check 0 - none or 1 - PixHawk_PWM for RPM Sensor Type, but not 2 - PIN)
I have tried to flash betta firmare and and found that appear possibility to set pin number as input but for the Sensor Type the same situation: value 0 and 1 only. I tryed to set the sensor type to 2 mannualy, but received as result -1 for RPM value in the Mission Planner.
Can sombody explane me is it possible to receive RPM data from pins to Mission Planner at all and how can I do this?
Thank you for any information in adwance
PixHawk is a hardware platform - micro computer.There are many different boards with Pixhawk arhitecture. On it you can put 2 kinds of software ie. different autopilot + ground station combo. This forum is for PX4 Autopilot and QGroundControl station software. Your questions are for APM Autopilot and Mission Planner ground control station.
You have to ask at: http://discuss.ardupilot.org/
Thank you for your answer
As I wrote in my previous, I am using PixHawk hardware autopilot (the clone of the PX4, marked as Pixhawk PX4 Autopilot PIX 2.4.8, like this http://image.dhgate.com/0x0/f2/albu/g5/M01/7A/CD/rBVaJFi4Q8KAa1uWAAfCAj141F8883.jpg ) with Plane Firmaware loaded.
As I know APM and PX4 are very different from each other in hardware and, therefore, and in software.
For this reason I believe that I have come to the right place 
I use the Mission Planner program as an autopilot firmware programmer, autopilot configuration program and to view the data transmitted from the autopilot using the MAVLink protocol.
That’s why I’m wondering why the option to select a pin for receiving an analogue signal of engine RPM data disappeared from the configuration of the autopilot and why this feature was left only in the Beta version of the firmware, but it also does not allow you to select the Type of source data _PIN (type 2 can be specified manually, but the data transfer does not provided anyway).
And, in fact, the main question is how to make PX4 transmit the RPM data I need according to the Mavlink protocol, as it was intended earlier. Very much surprised that no one needs it :(…
I myself have been looking into this same issue and very much interested in gather RPM data from the Pixhawk. Have you had any luck? I am currently using a 3DR Iris and Solo.
Was this ever solved? I need this too with exactly the same setup!
It sounds like you are using ArduPilot firmware on Pixhawk hardware, so you need to ask at discuss.ardupilot.org