Asset Framework Deep-Dive

AF Hierarchy Design

A well-designed AF hierarchy is the foundation of effective PI System deployment. The standard hierarchy follows industrial ISA-95 levels:

Enterprise
└── Site (Plant / Facility)
    └── Area (Production Area / Department)
        └── Unit (Process Unit / Line)
            └── Equipment (Asset)
                └── Component (Sub-asset)

Design Principles

• Reflect physical reality: Mirror your plant layout for intuitive navigation
• Normalize depth: Aim for 4-6 levels; deeper hierarchies slow queries
• Use templates: Never create elements without a template
• Separate concerns: Keep process hierarchy separate from maintenance hierarchy

Element Templates and Inheritance

Base Equipment Template
├── Name (String)
├── Location (String)
├── InstallDate (DateTime)
└── Status (String)

Pump Template (inherits Base Equipment)
├── [inherited attributes]
├── FlowRate (PI Point reference)
├── Pressure_In (PI Point reference)
├── Pressure_Out (PI Point reference)
├── MotorCurrent (PI Point reference)
└── VibrationLevel (PI Point reference)

Configuring a PI Point Data Reference

Attribute: FlowRate
Data Reference: PI Point
Configuration:
  Server: PISERVER01
  Tag Name: %Element%.FLOW_001
  (uses element name substitution for reuse across instances)

PI Analysis Service

Expression Analysis

// Calculate differential pressure
Attribute: DifferentialPressure
Expression: 'Pressure_In' - 'Pressure_Out'
Trigger: On Change
Output: Write to PI tag DP_001

Rollup Analysis

// Sum flow across all pumps in an area
Rollup: TotalAreaFlow
Function: Sum
Source: All child elements with FlowRate attribute
Output: AREA_TOTAL_FLOW
Trigger: Periodic (every 1 minute)

Event Frames

Performance Optimization

Scalability Guidelines

Hands-on Scenario: Condition-Based Monitoring

Step 1: Create Hierarchy

PumpStation_001
├── Pump_A (Centrifugal Pump Template)
│   ├── FlowRate → PUMP_A_FLOW
│   ├── Pressure_In → PUMP_A_PIN
│   ├── Pressure_Out → PUMP_A_POUT
│   ├── MotorCurrent → PUMP_A_AMPS
│   └── VibrationLevel → PUMP_A_VIB
└── Pump_B (same structure)

Step 2: Create Analyses

Analysis 1: DifferentialPressure
  Expression: 'Pressure_Out' - 'Pressure_In'
  Output: PUMP_A_DP

Analysis 2: EfficiencyIndex
  Expression: ('FlowRate' * 'DifferentialPressure') / ('MotorCurrent' * 0.746)
  Output: PUMP_A_EFF

Analysis 3: VibrationAlert (Event Frame)
  Start: 'VibrationLevel' > 8.5
  End: 'VibrationLevel' < 7.0