There are a number of global information exchanges related to industrial control systems security. They offer useful guidelines and standards to help protect the environment.
The UK Centre for the Protection of National Infrastructure (CPNI) provides good practice and technical guidance as well as advice on securing industrial control systems.
Secure move to IP-based Networks (SCADA):
They also highlight the risks of wireless connectivity of physical security systems
Similar information exchange centres were established in Japan and Spain,
For the introduction to Industrial Control Systems Security see my previous blogs (Part I, Part II, Part II) or ICS Security Library
Cyber Security Leadership 