Definition:
An Application Program is the specific logic developed and loaded into a safety logic solver or safety PLC to implement a Safety Instrumented Function (SIF).
Key Points:
- Must be created following strict software development life cycle (SDLC) principles.
- Typically programmed in languages like Function Block Diagram (FBD) or Ladder Diagram (LD).
- Subject to functional safety software standards like IEC 61508-3.
Example:
An emergency shutdown sequence programmed in a safety PLC using function blocks to process inputs from pressure transmitters and outputs to solenoid-operated valves.
See also: V-Model
Cited Source:
- IEC 61508-3:2010, Clause 7.4.