Download product list of an electronic invoice

Hello, I've been doing a lot of research, but I did not find any documentation, I'd like to know how to download the data of an electronic invoice (cpf client and product list) from rio grande do sul state (apparently each state has its own system), from bar code. I have an application that already reads the barcode, but returns a link to an interface page. from what I read, I should use a sefaz api, but the urls and parameters that I should send are not specified anywhere I've found. Would anyone know how to do this or where to find this information?