Decision D10 · 10 of 21
Writer protocol scope
OPC UA write only
RECOMMENDED
- Status
- RECOMMENDED — awaiting Vinayak
- Options
- OPC UA write only; Modbus write; vendor-specific
- Trade-offs
- OPC UA has security modes; Modbus has none
- Recommendation
- OPC UA write only, with security mode SignAndEncrypt and a per-plant certificate. Modbus and vendor protocols are not planned for writes.
- Why
- OPC UA has authentication and encryption; Modbus has none. Reads stay multi-protocol.
- Evidence
- EDGE
edge-agentreads OPC UA today; E26. - Reversible
- Yes, per plant, through a new decision.
- Blocks
- Writer, AL2 confirmed writes.
Page history: last 2 changes
- docs(research): retire stale research to archive/research-2026-10 with a register
ab84821 - docs(technical): split decision board into DECISIONS.md
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