Ok, perhaps I made some error, now I can receive the JSON Data and the BLOB there is:
[{"Cod_Cliente":"01230910","Denominazione":"CLIENTE1","Matricola_misuratore":"10433","Lett_Prec_Mis":"497","Lett_Rilevata_Mis":"1536","Codice_letturista":"L5","Foto_misuratore":"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
\/fzxXNz66mkXdnrA1fTipU6pArZ+5NII2H1VsEVJHqFq4O3U7Vsntcof61TasbJD47sNwtxEx77ZVP9akjM0hOzn6HNZtmliaH7WB\/qGJ+lSrPeAZMD8Dk4qHqMcl1OOsTfiOlK9xMy5MZJ9ah3CxVmuJME7Dz1qnPedix696RD3MjxRqKW3h\/UrgMcj
where "Foto_misuratore" is the BLOB field. Now must I to convert the BLOB (received like string) to Binary with su.DecodeBase64(...)?