55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
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---
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name: evolv-ot-edge-plc-integration
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description: Engineer OT edge connectivity and PLC interoperability for EVOLV. Use when implementing or reviewing OPC UA/Modbus and similar integrations, namespace/tag mapping, quality/timestamp semantics, retry/reconnect behavior, and deterministic command/feedback contracts at the edge.
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---
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# EVOLV OT Edge PLC Integration
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## Mission
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Deliver reliable, deterministic edge protocol integration between EVOLV Node-RED nodes and PLC/SCADA systems.
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## Harness Execution Contract
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- Start from current integration topology, topic contracts, and protocol endpoints.
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- Define invariants before edits:
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- command/feedback contracts remain deterministic
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- reconnect/retry behavior is bounded and observable
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- quality/timestamp semantics are preserved end-to-end
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- Validate with connection-loss and recovery evidence.
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## Scope
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- Edge/connector nodes (existing and new)
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- Topic mapping code in `nodes/*/src/`
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- Admin endpoints/config for connector behavior and credentials
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## Workflow
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1. Map PLC tags/NodeIds/registers to EVOLV message contracts.
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2. Define write acknowledgement and feedback confirmation rules.
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3. Implement reconnect/backoff/session handling.
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4. Enforce quality, timestamp, and stale-value semantics.
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5. Verify failover behavior and command idempotency.
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## Standards
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- Never assume connection continuity; model transient faults explicitly.
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- Keep protocol mappings versioned and auditable.
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- Separate transport errors from process-state errors.
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- Ensure secure defaults align with OT/IT security skill.
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## Test Expectations
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Cover:
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- disconnect/reconnect and session re-establish paths
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- duplicate/late/out-of-order message handling
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- read/write mapping correctness and unit conversion
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- safe behavior under degraded quality or timeout
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## Deliverables
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Return:
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- integration contract map (protocol <-> topic/payload)
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- retry/recovery strategy and limits
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- changed files/tests with failure-injection evidence
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- operational rollout risks and mitigations
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Decision interview triggers:
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- command authority or handshake behavior changes
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- protocol mapping breaks requiring migration
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- timeout/retry strategy changes affecting availability/safety
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