One of the 2 ways:
1- Use a DAQ Card and take analog outputs form Force Plate through this in Matlab Via Matlab Data Acquisition Toolbox. Resolve GRF and COP from Analog voltages using Calibration Matrix(if applicable) and Platform details such as Geometry, Origin etc.. You can also control start and stop of data collection.
2- Use Force Plate SDK to program in compatible language. This is direct, digital way and you can directly read, GRF components and COP.
Best way depends on specific conditions/requirements.