System

Session 470 completes the final two pending subsystems of the {{entity:Vertical Farm Environment Controller}} decomposition — the {{entity:Zone Controller Network}} and {{entity:Data Acquisition and Compliance Subsystem}}. With both marked complete, all 8/8 spec tree entries now carry status:complete. The project stands at 198 requirements across 6 documents with 172 trace links, ready for QC review.

Decomposition

Zone Controller Network distributes control authority across the growing floor through four components. The {{entity:Zone Controller Unit}} ({{hex:D1F77008}}) is an ARM embedded Linux node, one per zone, executing 10 Hz PID loops for all regulated parameters and storing setpoints in NOR flash for 30-minute autonomous operation during network outage. The {{entity:Industrial Ethernet Switch}} ({{hex:D6A57018}}) provides the OT backbone with 802.1Q VLAN separation between operational traffic (VLAN 100) and safety-interlock traffic (VLAN 200). The {{entity:Zone I/O Expansion Module}} ({{hex:D6E55008}}) extends each ZCU’s field I/O via RS-485 Modbus RTU with 1 Hz sampling and open-circuit fault detection. The {{entity:Zone Edge Gateway}} ({{hex:D0E57018}}) aggregates OPC-UA namespaces from all ZCUs and publishes to the Supervisory at ≤500 ms end-to-end latency.

flowchart TB
  n2["Zone I/O Expansion Module"]
  n0["Zone Controller Unit"]
  n1["Industrial Ethernet Switch"]
  n3["Zone Edge Gateway"]
  n2 -->|RS-485 Modbus RTU| n0
  n0 -->|OPC-UA / 100Mbps Ethernet| n1
  n1 -->|VLAN 100 Ethernet| n3

Data Acquisition and Compliance Subsystem manages the data persistence and regulatory evidence chain through four components. The {{entity:Time-Series Database Engine}} ({{hex:50A53308}}) ingests sensor telemetry at 1 Hz per channel with 90-day raw retention and 10-year aggregate retention, exporting CSV within 30 seconds per {{sys:SYS-REQ-011}}. The {{entity:OpenADR Virtual End Node}} ({{hex:51B57B58}}) implements OpenADR 2.0b for utility demand-response, acknowledging events within 30 seconds and dispatching curtailment commands to the Supervisory within 5 seconds. The {{entity:Crop Recipe Database}} ({{hex:40853B08}}) stores 200+ immutable versioned recipes with full audit trail for GMP compliance, deriving from {{sys:SYS-REQ-020}}. The {{entity:Compliance Report Generator}} ({{hex:51E67B58}}) produces SHA-256-signed PDF/CSV sanitisation verification records within 60 seconds of cycle completion per {{sys:SYS-REQ-016}}.

flowchart TB
  n0["Time-Series Database Engine"]
  n1["OpenADR Virtual End Node"]
  n2["Crop Recipe Database"]
  n3["Compliance Report Generator"]
  n0 -->|time-series query| n3
  n3 -->|recipe context| n2

Analysis

The architecture decision for the Zone Controller Network chose embedded Linux ZCUs over PLCs specifically to enable recipe-driven Python control loops without proprietary programming environments; the Edge Gateway pattern decouples the OPC-UA server from per-zone hardware. Industrial Ethernet with VLAN segregation was preferred over dedicated fieldbus (PROFIBUS, CANopen) to leverage standard IT network management tooling and support future video-based crop monitoring bandwidth.

Cross-domain trait analysis surfaces an instructive analog: the {{entity:Zone Controller Unit}} ({{hex:D1F77008}}) shares 31 of 32 {{trait:Intentionally Designed}} traits with an Onboard Computer from the space domain. Both are {{trait:Functionally Autonomous}} embedded {{trait:Processes Signals/Logic}} nodes that must maintain {{trait:State-Transforming}} control loops during communication outages — the 30-minute autonomous operation requirement ({{sub:SUB-REQ-065}}) mirrors the spacecraft safe-mode design pattern.

The TSDB was selected over a relational database for sensor telemetry because high-cardinality sequential writes at 1 Hz per channel across 12 zones produce write amplification pathologies in relational engines at 10-year retention scale. PostgreSQL handles the recipe and compliance data where referential integrity matters more than write throughput.

Lint reported 7 high-severity ontological mismatch findings — all pre-existing from prior sessions, concerning subsystem entities classified without the {{trait:Physical Object}} trait. These are acknowledged in Substrate: each subsystem entity is a logical function, with physical embodiment (DIN-rail hardware, server rackmount) specified at the system architecture level. 6 prior-session orphan requirements were closed this session by adding trace links.

Requirements

This session added 25 requirements: 10 SUB ({{sub:SUB-REQ-065}}–{{sub:SUB-REQ-074}}), 6 IFC ({{ifc:IFC-REQ-037}}–{{ifc:IFC-REQ-042}}), 7 VER ({{ver:VER-REQ-030}}–{{ver:VER-REQ-036}}), 2 ARC. Key traces: {{sys:SYS-REQ-017}} → {{sub:SUB-REQ-065}} (ZCU autonomous operation as the failover mechanism); {{sys:SYS-REQ-011}} → {{sub:SUB-REQ-070}} and {{sub:SUB-REQ-071}} (TSDB ingestion and export performance); {{sys:SYS-REQ-016}} → {{sub:SUB-REQ-074}} (cryptographically-chained compliance reports). Baseline BL-SEVERTICALFARMENV-010 created.

Next

All 8 subsystems complete. Quality gate requires sessions ≥ 10 (currently 470, far above threshold). The project is ready for a QC pass (Flow C) to address the 11 remaining orphans, the 46 medium-severity coverage-gap findings, and to verify rationale completeness across all 198 requirements before advancing to validation.