Control Sony A7S under DJI Matrice M600 drone

The most versatile solution is based on the AIR Commander Entire system as a remote camera controller and the AIR Commander Link v2 system as a long-range wireless link. AIR Commander Link v2 is a standalone wireless similar to other RCs, but focused on camera control. The Link simply transmits your commands from where you or your cameraman are standing to a remote location (drone, crane, cable camera, etc). The AIR Commander Link v2 receiver simply receives these commands and passes them to the cell, which executes them on your Sony A7S camera via multiport or WiFi. The connection between the AIR Commander Link v2 receiver and the Entire camera is very simple, just a single cable that includes power to the receiver. The connection cable is included in the basic package of the Entire. A basic operating diagram can be seen in the next picture.

You can also use the DJI Lightbridge 2 wireless connection from the DJI M600 drone as a control channel. For this solution you will need a DJI Expansion KIT for the DJI transmitter. This kit allows you to transmit custom commands through the Lightbridge to your drone's F-ports. Since the DJI A3's F-ports are PWM only, you will need to mix them using a PWM->SBUS converter. The SBUS will then connect to the Entire, where it will be converted into commands for the Sony A7S camera. This option is slightly less user friendly, but offers the full range of LightBridge2 control.
A basic schematic is shown in the next picture.