Radiolink Mini Pix - setup relay camera trigger

Hello! Could anyone help me to setup relay camera trigger on Radiolink Mini Pix FC - I use 3.6 firmware build from http://firmware.ardupilot.org/Copter/stable/mini-pix/arducopter.apj

When I used radiolink custom firmware relay worked on motor 5 port with setting RELAY_PIN=54

Now I am flashed http://firmware.ardupilot.org/Copter/stable/mini-pix/arducopter.apj and can’t find proper RELAY_PIN setting