Pease refer to the FX7500 support page. There you can find documentation and test&demo software (SeesionOne PowerSession) to make first steps.
Also you can get the SDK (EMDK) for Java, which enables you to write host based applications as well as applications running on the reader itself.
The FX7500 features digital outputs which you can use to trigger the boom barrier and inputs you can use for sensors or light barriers.
Depending on the complexity and ressource demands of your software you may decide, if it is OK to run it on thre reader or to put it on an external controller or host.
The application usually defines filters for the Tags, selects the Tags that need to be accessed, triggers the read cycle and derives the buffered Tag data from the reader.
There is sample code to begin with. The samples come with the EMDK.