24.2 INSTRUCTION TYPES
· There are basic categories of instructions,
-
Basic (discussed before)
-
- relay instructions
-
- timer instructions
-
- counter instructions
-
Program Control
-
- branching/looping
-
- immediate inputs/outputs
-
- fault/interrupt detection
-
Basic Data Handling
-
- moves
-
- computation instructions
-
- boolean instructions
-
- conversion
-
Logical
-
- comparisons
-
Advanced Data Handling
-
- file instructions
-
- shift registers/stacks
-
Complex
-
- PID
-
- communications
-
- high speed counters
-
- ASCII string functions
· The reader should be aware that some functions are positive edge triggered (i.e. they only work the scan is active). while most are active any time the input is active. Some examples of edge triggered and non-edge triggered functions are listed below,
-
Edge Triggered
-
CTU, CTD
-
Non-edge triggered
-
TON, TRO, TOF, ADD, MUL, etc.