Well, I did some more digging. I created the diagnostic screen, numbered it '99' and ran the program. Whenever the screen disappeared, I checked the diagnostics and found absolutely nothing out of the ordinary.
I ended up cheating and creating a work around for the problem. Whenever fault code changes to '0', the PLC will now automatically change it to '3'. The HMI will now display a "System Normal" message whenever it sees a value of 3. It's a crappy cheat, but whatever - I can't afford to spend any more time on it.
Thanks for all your help guys.
Mark
I ended up cheating and creating a work around for the problem. Whenever fault code changes to '0', the PLC will now automatically change it to '3'. The HMI will now display a "System Normal" message whenever it sees a value of 3. It's a crappy cheat, but whatever - I can't afford to spend any more time on it.
Thanks for all your help guys.
Mark
