Industrial telemetry & communications diagnosticsSaint Paul · On-site across the Twin Cities
ALANEEDSYSTEMS
Sample deliverable / 01

Follow the finding
back to the evidence.

A compact example of how we document a discrepancy, its limits and the next useful action.

Fictional worked example — not customer work.
All equipment, readings and findings below are invented to demonstrate the report format.
Alaneed Systems / Findings report

Field-to-SCADA value discrepancy

EXAMPLE 01
Reported symptom
The SCADA flow display shows a value ten times higher than the field instrument.
Scope
One flow measurement, from the field display through the PLC and gateway to one SCADA display. Three stable observations during a fictional 30-minute period. No configuration changes.

01 / Observations

All displayed values are labeled L/min. The gateway’s outgoing numeric value is expected to use the same unit.

Illustrative readings in L/min
ObservationField displayPLC valueGateway outputSCADA display
1252525250
2505050500
3757575750

Matched: the field display, PLC value and gateway output agree at all three observations.
Mismatch: the SCADA display is consistently ten times the gateway output.

02 / Finding and confidence

The first observed discrepancy lies between the gateway’s outgoing value and the SCADA display. An extra scaling conversion is a plausible explanation, but these observations do not establish the exact configuration responsible.

Observed mismatch: high confidence within this example.

Proposed cause: provisional until the receiving tag’s mapping, units and conversion settings are reviewed.

03 / Limits and items not tested

  • Actual flow accuracy or instrument calibration.
  • Electrical signal integrity between the instrument and PLC.
  • Behavior outside the three observed values or observation period.
  • Historian records, alarms, control logic or other tags.
  • The configuration responsible for the discrepancy.

Agreement between displayed values does not establish that the underlying physical measurement is accurate.

04 / Prioritized next actions

  1. Have the customer’s authorized SCADA owner inspect the receiving tag’s mapping, units and scaling settings.
  2. Document any proposed correction and obtain customer approval before authorized staff make changes.
  3. Repeat the comparison across the expected operating range after any correction.
  4. Check related historian values and alarms separately if they use the same measurement.
Recommended next decision

Complete the configuration review before choosing a corrective action.

End of fictional worked example · Actual reports reflect the agreed scope and available evidence.

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Fictional worked example

Reconciling meter and historian totals

A separate submetering example: three totals for the same meter and the same 30-day period.

The physical meter pulse count and Modbus register total at the gateway both equal 12,438 kWh. The historian records 11,104 kWh, a shortfall of 1,334 kWh or 10.7 percent. Agreement localizes the discrepancy downstream; it does not independently validate meter calibration.

Fictional worked example. No customer data.

Finding: Meter pulse and field-bus totals agree. The historian records 10.7% less. The discrepancy lies in the gateway-to-historian data path for this period.

Evidence limit: Assumes aligned start/end readings, units and pulse conversion, with no unresolved rollover or reset. The cause of the shortfall is unproven; agreement between meter outputs does not verify calibration.

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