Abstract: With the deep integration of industrialization and informationization and the rapid development of system network interconnection,the issues of information security in EPLC attract more attention．This paper proposed a two-level control framework to ensure the information security．Detection based on attack signature database is employed to draw up the control schemes for the identifiable instructions at the inner level．And at the external level,redundancy techniques are used to conquer the unidentifiable instructions which are detected based on system models．Finally,a test EPLC platform on CortexA8-Linux was established to realize and verify the proposed approach,and the experimental results show that the EPLC not only could meet the real-time requirement,but also could detect and process those external instructions well．

Key words: Embedded PLC, Linux,Information security,Intrusion detection,Intrusion processing