More and more facilities are being connected to the Internet, also indirectly by normal office business systems. This will industrial workshop is exposed to each individual computer users are very familiar with all kinds of safety problem. Computer hacking has become a more targeted. Hackers will their virus software and important security features only send several computers together, usually for the purpose of industrial espionage. This means that the virus and Trojan can remain undetected for a long time, before caught by antivirus software, they have caused the damage.

    Thus effective plant and data protection must provide a full range and depth of the protection. Siemens based on ISA 99 above the concept of "defense in depth" conforms to the standard, the ISA 99 was applied in three levels: plant security, network security and access protection.