PLC's and Safety and Hacking

Hi all
If you have time, please read this thread on the SoundOff blog that I have been taking part in. It is about security and safety systems. I am very interested in what this community thinks about the risks etc. And what you do to ensure that the systems you provide are safe from hackers.

Francis

Hmmm

Cons :
First I guess the web address , then i guess the address of the valve to open
Pros : Anything connected to the net should be firewalled and the more people are aware , the better