About screen updating

I want to learn how does  the scope works on screen updating, is PC software query hardware periodically or hardware send data to PC receiving buffer automatically then trigger the plotting area continuous updating? Or tell me which module's code should I read, please someone helps, thank you very much.

The hardware will automatically send data to the PC, if the PC software is ready to accept it.

First (when the trigger is detected) the data will be saved to onboard RAM. At the same time when the data is being saved to RAM, the FPGA will start sending the saved data from RAM to FX3. The FPGA will check FX3 USB endpoint flags which indicate when PC can receive data. The FPGA will continuously send data, if the USB endpoint FIFO is not full. It will stop sending data when the USB endpoint flag is asserted and wait until the endpoint is ready to accept data again.

Dear Dejan
Thanks, it's clear about hardware now, but I'm still confuse on PC software, the software screen will updating in real time when hardware was set to veido trigger mode, could you please explain how the software works on screen updating?was it implemented by reading USB in buffer circularly？ or maybe just tell me which part to read in the project source code, there is too much code in the whole project to read.Thanks again.

Yes, the PC software periodically queries the hardware (USB endpoint) and reads the data. The software reads the data from USB endpoint (one USB packet is 1024 Bytes) until the complete frame size is reached. There are low level USB functions written in the software which read the raw data from USB endpoint. Other software functions call these low level functions, for example to display the data or make calculations. When PC software reads the USB buffer, the hardware will detect this and automatically fill the USB buffer with new data.