Pixhawk 4 and iBUS

I am trying to connect my receiver FS-iA6 to my Pixhawk 4 on DSM/SBUS RC or PPM RC. I thought it would work with PPM RC but in QGroundControl app it still shows me that 0 channels are active. Do I need to use ppm encoder for that, if yes then can you please tell me which one?

Thanks in advance