The LOA assessment classifies every unit operation and procedure in your facility across a structured Level of Automation matrix — determining whether each should be Manual, State-Based Control (SBC), Sequence-Based Control (SqBC), or fully automatic.
This is a critical design decision point in the ISA‑106 work process. The LOA output directly defines the scope and architecture of the URS and FRS that follow. Getting it right before committing to detailed design saves significant rework cost downstream.
Before any User Requirement Specification can be written, the engineering team must agree on what level of automation is appropriate for each procedure and unit operation. This is the LOA assessment.
Assigning the wrong LOA — too high or too low — leads to over-engineered or inadequate automation. Both outcomes cost more to fix after implementation than during the design phase. The CDL LOA service ensures these decisions are made systematically, with the right stakeholders, against a consistent matrix.
The unit operation is governed by defined operational states with automatic transitions between them. The DCS monitors process conditions and moves between states without operator intervention — while still allowing manual override.
The unit operation follows a defined ordered sequence of steps — typically for batch operations, startup/shutdown procedures, or processes where step order is critical and non-negotiable.
Some operations are better left as manual or operator-assisted — particularly where process variability is too high, consequences of automation failure are severe, or frequency is too low to justify the engineering investment.
Each Unit Module and operation in your plant is evaluated against the following six-level LOA matrix. The CDL service engagement leads your team through this classification systematically, with documented rationale for each decision.
| Level | Classification | Operator Role | DCS Role | ISA‑106 Type | CDL Tooling |
|---|---|---|---|---|---|
| L0 | No Automation | Executes all steps manually without DCS support or guidance | None — DCS is not involved in the procedure | Manual | Not applicable — no SBC design required |
| L1 | Operator Initiated & Guided | Initiates each step and follows DCS prompts and guidance displays | Displays step instructions, monitors conditions, and alerts on deviations | Assisted | Operator guidance pages via P6 FRS; no ACM code generation |
| L2 | Semi-Automatic | Confirms each step before DCS proceeds; retains authority over sequence progression | Checks pre-conditions and executes the step action upon operator confirmation | Semi-Auto | Step logic in P6 FRS; partial ACM code via P7 |
| L3 | State-Based Control | Monitors operation; can intervene, override, or hold at any time | Manages operational states and executes transitions automatically based on process conditions | SBC | Full URS (P5) → FRS (P6) → DDS → ACM Code (P7) |
| L4 | Sequence-Based Control | Monitors operation; authorises start of sequence; can abort | Executes ordered step sequence automatically; manages interlocks and transition conditions | SqBC | SOP (P4) → URS (P5) → FRS (P6) → ACM Code (P7) |
| L5 | Fully Automatic | No routine intervention required — supervision only | Initiates, executes, and completes procedures autonomously based on process triggers | Auto | Full CDL pipeline P1‑P7; advanced control integration |
The LOA service is delivered as a structured workshop engagement with your process control and operations engineering teams. It typically follows a completed IPA (P1) — using the loop performance and operability findings to inform the classification decisions.
The LOA decision is one of the most consequential choices in the ISA‑106 work process. It cannot be automated — it requires experienced process control engineers working with your team's operational knowledge.
The workshop format brings operations, process control, safety, and management stakeholders together — ensuring LOA decisions reflect the full range of operational requirements and constraints.
Every classification decision is documented with the reasoning behind it — creating an auditable record that supports future modifications and regulatory review.
A wrong LOA decision discovered during detailed design (P5/P6) or commissioning is expensive to fix. Getting it right at P2 is the most cost-effective quality gate in the entire CDL pipeline.
When P1 IPA has been completed first, the LOA classification is informed by actual plant performance data — loop rankings, oscillation findings, and operability indices — not just engineering assumptions.
A comprehensive presentation of the LOA service — scope, methodology, deliverables, and fit with your project — is available by Zoom. Contact us at info@CtrlDesigner.com with your company email to request a session.