I suppose you would like to control airpick by coding an application in C or other languages.
To do that you need to have a Modbus RTU library that will help you communicate with the gripper.
example of C library: https://libmodbus.org/
With Modbus RTU library, you can read and write airPick register which is what you have to do to control it.
It is like writing in airPick memory register: "Make vacuum at 70%", "release", ...
You will find details about modbus RTU control in airpick manual:
https://assets.robotiq.com/website-assets/support_documents/document/AirPick_Instruction_Manual_e-Series_PDF_20190912.pdf
I have a question , I use visual studio to control motor and airpick . I already can use user interface control , but I don't know how to autocontrol after connecting COM. I just need to control pick and place .