The Blackmagic Design ATEM switcher lacks a TCP port, making it difficult to integrate with AV equipment. The SKAARHOJ TCP Link for ATEM Interface, developed by SKAARHOJ, gives a simple TCP interface to practically every function in the switcher. It will notify switcher status changes as well as accept and pass commands to the switcher. Exactly what you need for AV projects including various AV systems such as Crestron, Extron, and others.

Connect to the device through TCP, then alter the required command on the ATEM switcher, and the TCP Link for ATEM will output how the command looks in the terminal, which you may use to transmit the same command to the switcher.