| Function block group (FB) - Control |
| FB - Variables |
| FB - Math |
| Data flow |
| FB - Data |
| Execution direction |
| FB - Logic |
As shown above:
- A control logic program consists of a main loop and several command lines. After all commands are executed, the execution restarts from the first command line.
- Each command line consists of one or more function blocks that run from top to bottom. Data within command lines flow from right to left.