IEC 61131-3: International standard for PLCs that defines the following programming languages:
- Ladder Diagram (LD)
- Function Block Diagram (FBD)
- Structured Text (ST)
- Instruction List (IL)
- Sequential Function Chart (SFC)
SR - bistable function block, set dominant
RS - bistable function block, reset dominant
R_TRIG - raising edge detection
F_TRIG - falling edge detection