The operator should see a steadily increasing volume, not a repeated sum of flow-rate samples. For a constant input of 60 GPH, the accumulator must add 60 gallons in one hour. A result near 3,600 gallons is a 60× timebase error: the configuration is treating each minute's 60 GPH reading as 60 gallons.
What is the screen telling you?
Start with the live values shown on the mimic. Read the source analog point and accumulator at the same time, then record the accumulator again after a measured interval. The expected volume change is:
Volume change = Flow in GPH × elapsed seconds / 3600
At 60 GPH, the expected increase over 10 seconds is 60 × 10 / 3600 = 0.1667 gallons. After one hour, the increase must be approximately 60 gallons. Use the actual elapsed timestamps when the input varies.
| Observed result | Meaning | Next check |
|---|---|---|
| About 60 gallons after one hour | The rate-to-volume conversion is correct | Check the display and historical bindings |
| About 3,600 gallons after one hour | Each minute's GPH reading is being counted as gallons | Inspect the accumulator timebase and scaling |
| Accumulator does not advance | No accepted source update, bad quality, or wrong source binding | Trace the analog point through the driver |
| Live total is correct but the hourly historical value is wrong | The tag is right; the historical binding or aggregate is wrong | Inspect the trend aggregate |
Does the analog point really represent GPH?
Trace the displayed rate backward from the mimic to the analog point, driver, and controller. Confirm that the controller value is an instantaneous flow rate expressed in gallons per hour. A rate cannot be accumulated correctly until its engineering units and update behavior are known.
- Read the raw controller value and the corresponding ClearSCADA analog point value.
- Compare their engineering ranges and scaling. A driver or point scale must not convert the value a second time.
- Record two or more point timestamps. Identify whether the driver reports periodically, by exception, or only when the value changes.
- Check point quality while taking the readings. Do not interpret a stale retained value as a fresh measurement.
The random input varying from 60 to 60.000001 forces value changes, but it does not correct dimensional scaling. It can prove that value-change processing receives updates; it cannot prove that the accumulator converts hours to seconds.
Where does the 60× error enter?
An end-of-period interval defines when a total resets or rolls into a new period. It does not convert GPH into gallons. Setting an end-of-period interval to one hour therefore cannot repair a rate that is being summed as if every reading were already a volume increment.
For discrete samples, calculate each increment from the sample duration:
ΔV = F × Δt / 3600
where F is GPH and Δt is seconds. With a fixed 10-second interval, the scale per sample is 10 / 3600. If the accumulator evaluates once per second, converting GPH to gallons per second with F / 3600 produces the same result. These configurations both work only when their assumed evaluation intervals match actual execution.
| Setting or value | Location or role | Effect |
|---|---|---|
Continuous |
Accumulator processing | Keeps the total active rather than limiting it to an isolated report |
Timed Report Int: 10S |
Historical reporting | Schedules stored reports; it does not by itself supply the GPH-to-volume divisor |
Timed Report Offset: M |
Report alignment | Aligns report timing; it does not change engineering units |
EOP Int: 0 |
End-of-period reset | Disables periodic reset, matching a total that runs until an operator resets it |
| Historic filters selected | History configuration | Controls recorded or retrievable data, not rate integration |
Is the live display bound to the accumulator?
When the accumulator math is correct but the screen remains wrong, inspect the mimic binding. The displayed object must reference the accumulator's current value, not the original analog flow point, a historical aggregate, or a calculation with different units.
- Open the display object's binding and identify the exact source object.
- Compare the bound value with the accumulator value in the database.
- Check the display's unit label and decimal formatting. Formatting can conceal small 10-second increments but cannot create a 60× error.
- Exercise the operator reset and confirm that it targets the accumulator, not the source analog point.
Keep EOP Int: 0 when the operating requirement is manual reset only. Apply the reset through the configured operator control and access permissions. A scheduled one-hour reset serves an hourly batch total, which is a different requirement from a continuously running total.
Why is the historical hourly total wrong?
A cumulative total is already an integrated value. Applying a historical Total aggregate to its samples sums repeated snapshots of that cumulative value and produces an inflated result. For example, ten stored snapshots of a counter near 100 gallons do not represent 1,000 gallons of new flow.
Choose the historical calculation according to the question being asked:
| Required screen value | Bind or calculate from | Reason |
|---|---|---|
| Current volume since manual reset | Current accumulator value | The accumulator already contains the running integral |
| Volume added during an hour without a reset | End value minus start value | The difference represents counter movement during the interval |
| Integrated hourly volume from flow-rate history | Time integration of the analog rate | The calculation incorporates elapsed time between rate samples |
| Sum of discrete volume pulses or increments | Historical total of increments | Summation is valid because each record is already a volume |
If the accumulator can reset inside the historical interval, a simple end-minus-start result becomes invalid. Split the interval at the reset or calculate from the original rate history. The reset timestamp is the reading that decides which method applies.
How should the fix be applied and verified?
- Confirm that the source analog point is GPH and that its live value matches the controller value.
- Set the accumulator to run continuously and retain
EOP Int: 0for operator-only reset. - Convert the rate to a volume increment using the real evaluation interval. Use
F / 3600only when the converted value is integrated once per second. For a fixed 10-second discrete sum, useF × 10 / 3600. - If scan or report spacing can vary, use timestamp-aware rate integration rather than multiplying every sample by a nominal 10 seconds. This prevents communication delays and missing reports from distorting the total.
- Bind the live mimic field to the accumulator's current value.
- For an hourly historical display, use counter difference or rate integration instead of totaling cumulative snapshots.
- Reset the accumulator, hold the test source near 60 GPH, and record the total after 10 seconds and one hour. Expect about 0.1667 gallon and 60 gallons respectively, with allowance for measured flow variation and actual timestamps.
FAQ
Why does my ClearSCADA flow total read 60 times too high?
The configuration is counting GPH samples as volume without converting the sample time to hours. Apply ΔV = F × Δt / 3600; an hourly end-of-period setting does not perform that conversion.
Why does the historical Total disagree with the live accumulator?
A historical Total can sum cumulative counter snapshots, inflating the result. Display the current accumulator for volume since reset, or use end-minus-start for an interval with no reset.
How do I verify a ClearSCADA GPH totalizer?
Reset it, apply a stable 60 GPH input, and compare timestamped readings. The final verification is an increase of about 0.1667 gallon after 10 seconds and 60 gallons after one hour.