Logic is performed in the controllers using numbered function codes and specs for each function code.
Function Codes are standard logic structures (ex. AND, OR, Timers, PID etc.). Function Codes use up blocks in the controller. Some function codes use up multiple blocks. Controllers usually allow 10,000 blocks.
The system uses redundant controllers (primary and backup).
Conventional Software Tags do not exist in the controller. They exist in multiple databases. (Composer and HMI).