RFID systems are complex heterogeneous systems, consisting of hardware and software components. These systems are more and more used in many types of applications, some of which are critical and need fault-tolerance mechanisms. However, most existing work on RFID systems deal with security aspects related to data integrity and confidentiality and less with dependability aspects (fault-tolerance, reliability, etc.) In this paper we present an overview of existing RFID middlewares and fault-tolerance approaches. We propose a global test and diagnosis approach implemented at the RFID middleware that is intended to detect and locate faulty tags and readers to allow their isolation from the system. This work is part of the French ANR project SAFERFID (Dependability of RFID Systems)