This is a Geo SCADA Expert specific algorithm.
The Max Last algorithm calculates a maximum value based on:
- The last raw historic value before the start of the resample interval
The last raw value isn't used if the first raw value in the interval occurs at exactly the start of the interval.
- The raw historic values in the resample interval.
To calculate the Max Last value, Geo SCADA Expert:
- Examines the raw historic values in the sample and the last raw historic value before the sample if it does not occur at exactly the start of the interval.
- Returns the highest value of those values examined in Step 1. This is the Max Last result and it has a timestamp that matches the start time of the sample.
The results returned by the algorithm do not depend on the quality of the data. You can choose to filter the data on quality using the Qualities combo box in the Edit Source window (see Configure a Trace)
Like the Max Interpolated algorithm, the Max Last algorithm is useful when there are gaps in the data - it allows a maximum value to be calculated for time periods where there are no raw historic values. However, the Max Last algorithm only uses actual raw historic values, unlike the Max Interpolated algorithm which uses two estimated historic values (the interpolated values).
Example:
A trace is configured to use the Max Last algorithm and is set to have a resample interval of 1M (1 minute). This means that for each 1 minute sample, Geo SCADA Expert will calculate a maximum last value.
At 10:31, Geo SCADA Expert has to plot an maximum last value on the trace. To do this, it compares the last raw historic value from before 10:31 to each of the values in the sample (10:31 - 10:32). In this case, the values are:
| Timestamp | Raw Historic Value |
|---|---|
| 09:59:55 | 33.40 |
|
10:31:05 |
29.11 |
|
10:31:10 |
27.48 |
|
10:31:20 |
30.32 |
|
10:31:30 |
30.34 |
|
10:31:40 |
34.12 |
|
10:31:50 |
30.43 |
This means the max last value is 34.12 (the highest value). This value is plotted on the trace at 10:31.
Further Information