Interlockat

Interlockat is a term used in industrial automation to describe a framework or protocol for implementing interlocks across multiple devices and processes to enforce safety-critical sequencing. The concept blends traditional mechanical and electrical interlocks with stateful software coordination to guarantee that certain actions occur only when prerequisite conditions are satisfied.

Implementation can be centralized or distributed. In a typical interlockat deployment, devices publish status indicators and desired actions to a coordination service. A controller evaluates safety rules and interlock conditions, allowing or denying commands based on current states, sensor inputs, and fault status. The model supports mutual exclusion, sequencing, and fault handling, including timeouts and safe states, and it maintains audit logs for traceability. Interlockat emphasizes verifiable state machines and deterministic behavior to avoid race conditions and hazardous overlap of equipment actions.

Applications include automated manufacturing cells, robotic workstations, automated storage and retrieval systems, and process lines where multiple subsystems must coordinate with guaranteed safe handoffs between steps.

Although described in industry writings, interlockat is not a formal standard. It is used as a conceptual approach to safety coordination, often implemented alongside established standards such as IEC 61508 or ISO 13849 in order to achieve appropriate safety integrity levels. Compatibility with existing control architectures (PLC, DCS, or HMI layers) and with common industrial communication protocols is a practical consideration.

Limitations include added system complexity, integration effort, and potential performance overhead. Proponents emphasize the benefit of improved safety, traceability, and predictable behavior in multi-device environments.

See also: interlock; safety interlock; control system; PLC; distributed control system.