Glossary · System coordination, integration and orchestration
Coordination logic
Also known as: interlocking logic (operational), sequence coordination logic
German: Koordinationslogik
In control software, coordination logic is the part of a program that governs the interaction between machines, stations or functions, for example handshakes, resource reservations and synchronization of sequences, as opposed to the logic that controls individual actuators.
- System integration
In one sentence
Coordination logic is the program logic that governs how machines, stations or functions interact through handshakes, reservations and synchronization.
Example
The coordination logic in the cell PLC allows the robot to enter the press only when the press reports its ram at top dead center and its cycle finished.
How it applies
- Engineering: Structure coordination logic as explicit state machines with named states and transitions; implicit coordination through scattered bits is hard to test and review.
- Verification: Test coordination logic with simulated partners, including partners that respond late, twice or not at all. Many interaction hazards (see Interaction hazard) arise from coordination errors, not from single-machine faults.
- Documentation: Describe coordination logic in the software design document with state diagrams and signal tables. Troubleshooting sections in manuals should explain which coordination state a waiting machine is in and what it waits for.
Coordination logic vs. safety logic
Coordination logic prevents collisions and faulty sequences during normal operation. Safety logic implements safety functions with the integrity required by the risk assessment. Coordination logic must not be credited as a safety function unless it has been designed and validated as one.