Adapter for converting Avalon-MM data to Avalon-ST data

I haven't used that FIFO but I think you setup the control register for SOP generation, then write your data, then you disable the SOP generation, keep writing data, then on the last beat you setup the control register to generate EOP, then write your data. So generating SOP or EOP requires control information to be written first so you'll need the control slave to be enabled. Once enabled I would take a look at the user guide for that IP core to see what the register format is to control the FIFO. The user manual should be hyperlinked so that when you click on the documentation button with the FIFO GUI open it should automatically bring you to the IP manual.