How use Serverboard IO from CM4

[Helmut_number_one]

I'm new here and don't have a server from here yet, my question:
How do I communicate with the analog and digital inputs and outputs from Server Board to the CM4 System,
with Modbus TCP, UDP, MQTT or with firmware commands?
Example I want to read the analog input from the board to CM4 and assign a value to the analog output from board.
I can use MQTT, UDP, Modbus TCP or Http Get/Put.
I use it with PHP Server Script IP-Symcon Homeautomatic system
Best regards