Understanding AF Attribute Calculations
OSIsoft ProcessBook displays process values that often come from PI tags, AF attributes, or both. This calculator models that workflow in a practical way. It lets you enter several AF attribute readings, assign a weight, and describe how long each reading applied. The result can support checks, mockups, reports, and training examples.
Why Weighted PI Logic Helps
A single process value may not show the full condition of an asset. One pump may need flow, pressure, vibration, temperature, and efficiency together. AF attributes can organize those values under the asset. A weighted formula then lets important attributes influence the final score more than minor attributes. This is useful when a display needs one clear value.
Time And Quality Factors
ProcessBook displays may include calculated values over an interval. A reading that lasts ten hours has more impact than a reading that lasts one hour. The time weighted average handles that idea. Quality also matters. Bad data, stale values, or lab delays can reduce confidence. This calculator applies a quality percent to the display score.
Availability And Target Review
Availability compares operating time with downtime. If total hours are twenty four and downtime is two, availability is based on twenty two active hours. The scaled value is then compared with a target. The deviation shows whether the process is above or below the desired value. Tolerance helps decide if the result needs attention.
Using The Output
The result block shows weighted average, time weighted average, scaled value, deviation, availability, quality adjusted display score, and an overall process index. These values are estimates for planning and comparison. They do not replace a configured PI Analysis, AF analysis rule, or validated plant calculation. They are best for learning, documenting display logic, and checking assumptions before a production change.
Practical Display Planning
Before building a final ProcessBook display, confirm each AF attribute path, unit, and update frequency. Check whether values are averages, snapshots, totals, or manual entries. Align units before weighting them. Keep the final formula simple enough for operators to trust. Export the result and example table when you need a quick review record. Store notes beside each calculation so future reviewers understand the selected weights and source assumptions.