IEC 61499 (Deprecated)

Status: Superseded by IEC 61131-3

As of March 2026, the Cloud-Native DCS control execution layer has migrated from IEC 61499 (event-driven function blocks) to IEC 61131-3 (cyclic scan function blocks).

The IEC 61499 execution model, Execution Control Charts (ECC), and composite function blocks have been removed. The runtime now uses a standard IEC 61131-3 cyclic scan loop where all blocks execute in declared order each scan cycle.

What was kept from the original implementation: - All standard function block types (DI, DO, AI, AO, PID, TON, TOF, TP, CTU, CTD, SR, RS, R_TRIG, F_TRIG, logic, math) - Data connections between blocks - Device driver interface (Modbus, EtherNet/IP, OPC UA, simulation) - Runtime deployment via Kubernetes controllers - Hot-swap, content verification, persistence

What was removed: - Event-driven scheduling (event connections, event-only block kinds) - RunToCompletion (oneshot) execution mode - Composite Function Blocks (CFB) with event boundary mapping - Basic Function Blocks (BFB) with Execution Control Charts (ECC) - Guard expression evaluation

New CRDs: - ControlProgram replaces FBNetwork - FunctionBlockType replaces FBBlockType

See IEC 61131-3 Compliance for current traceability.