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The Totalizer tag provides a means of accumulating the sum of another tag's (or calculation's) value over time. To put it more precisely, the totalizer integrates a value over a time period.
The totalizer looks for its source to represent values "per second", "per minute" or "per hour". It is important to select a source time scale that matches the source values. For example, when recording total flow from a meter that is measuring flow rate per second, selecting the "per minute" source time scale is guaranteed to produce results that are incorrect.
You can also use the totalizer to record running time. For this, the source value must be a 1 when the equipment is running and a 0 when stopped. Given a source time scale of "per second" this will add 1 second, per second while the equipment is running and 0 seconds per second while stopped.
An invalid is not taken to mean that the value (or running state) of the tag is 0. If the source's value goes to invalid, it will be assumed that the last known value remains in effect and that value will continue to be used for the integration.
Values are added to the Totalizer tag at the end of each elapsed source time scale. This will not necessarily be "on the second" or "on the minute".
Do not attach a Logger tag to the Totalizer. At the end of each log interval, values are logged using the built-in connection to an Historian. You have the option of performing a reset of the Totalizer tag's value after each write to the log file.
You can cause a reset to be done at times other than the set logging interval, either by providing a reset button for the operator to use, or by configuring a tag to use an external reset. The current value is always logged before a reset is done.
If the totalizer is drawn with a Set Analog Value tag or a Numeric Entry tag, two things will happen when the operator uses either widget: the totalizer will log its current value and it will reset to whatever value is set by the widget instead of 0.
It should be noted that a plot of the Totalizer tag on the Historical Data Viewer will show a constant value from one log interval to the next, with an instant change between values at each log interval.
The current value of the Totalizer tag is saved between VTScada restarts.
Do no attempt to attach a Logger tag to a Totalizer tag. Totalizer tags have built-in logging.
Difference from the History Statistics tag, totalizer option:
The Totalizer tag calculates a time-weighted integral of the values collected. The totalizer option of the History Statistics tag provides a sum of the values within the time interval. Both have their uses.
Totalizer properties ID tab
The ID tab of every tag includes the same common elements: Name, Area, Description, and Help ID.
Name:
Uniquely identifies each tag in the application. If the tag is a child of another, the parent names will be displayed in a separate area before the name field.
You may right-click on the tag's name to add or remove a conditional start expression.
Area
The area field is used to group similar tags together. By defining an area, you make it possible to:
- Filter for particular tag groups when searching in the tag browser
- Link dial-out alarm rosters to Alarm tags having a particular area
- Limit the number of tags loaded upon startup.
- Filter the alarm display to show only certain areas.
- Filter tag selection by area when building reports
When working with Parent-Child tag structures, the area property of all child tags will automatically match the configured area of a parent. Naturally, you can change any tag's area as required. In the case of a child tag, the field background will turn yellow to indicate that you have applied an override. (Orange in the case of user-defined types. Refer to Configuration Field Colors)
To use the area field effectively, you might consider setting the same Area for each I/O driver and its related I/O tags to group all the tags representing the equipment processes installed at each I/O device. You might also consider naming the Area property for the physical location of the tag (i.e. a station or name of a landmark near the location of the I/O device). For serial port or Roster tags, you might configure the Area property according to the purpose of each tag, such as System or Communications.
You may define as many areas as you wish and you may leave the area blank for some tags (note that for Modem tags that are to be used with the Alarm Notification System, it is actually required that the area field be left blank).
To define a new area, type the name in the field. It will immediately be added. To use an existing area, use the drop-down list feature. Re-typing an existing area name is not recommended since a typo or misspelling will result in a second area being created.
There is no tool to remove an area name from VTScada since such a tool is unnecessary. An area definition will exist as long as any tag uses it and will stop existing when no tag uses it (following the next re-start).
Description
Tag names tend to be brief. The description field provides a way to give each tag a human-friendly note describing its purpose. While not mandatory, the description is highly recommended.
Tag descriptions are displayed in the tag browser, in the list of tags to be selected for a report and also on-screen when the operator holds the pointer over the tag’s widget. For installations that use the Alarm Notification System, the description will be spoken when identifying the tag that caused the alarm.
The description field will store up to 65,500 characters, but this will exceed the practical limits of what can be displayed on-screen.
This note is relevant only to those with a multilingual user interface:
When editing any textual parameter (description, area, engineering units...) always work in the phrase editor. Any changes made directly to the textual parameter will result in a new phrase being created rather than the existing phrase being changed.
In a unilingual application this makes no difference, but in a multilingual application it is regarded as poor practice.
Help Search Key
Used only by those who have created their own CHM-format context sensitive help files to accompany their application.
Totalizer properties Settings tab
Source
The source can be any tag, calculation or even a constant. Whatever value is provided here will be the value that is totaled. In most cases, this will be an analog status or Analog Input tag, but there are no restrictions on the source. You might use a digital input to collect a total of equipment running time. If, for example, you specify a constant value of 1, the totalizer will record the total time that the application is running.
Source Time Scale
While there is no limitation on what can be used for the source, a Totalizer tag will commonly be used with equipment such as a flow meter. Flow meters may provide their values in units of flow per second, flow per minute or flow per hour. Selecting the correct time scale is of critical importance to collecting an accurate total.
Log Interval
The Totalizer tag will record its current total to a log file at the end of each interval specified. This interval goes by the clock, not by running time. If, for example, the log interval is set to "Day" the tag's value will be logged at midnight, not at the end of 24 hours of operation. If the log interval is set to "Hour" the tag's value will be logged each hour on the hour. Weekly means midnight on Sunday night and Monthly means midnight starting the first day of the month.
Reset After Log
You can select whether the totalizer should be reset to 0 after its value is logged.
Zero Cut-off Limit
To allow for a source that does not output an exact 0 when there should be no value to record, you can set a zero cut-off limit. This value is taken as a range, above and below zero, within which the totalizer takes 0 to be the source's value.
Note that this is a range above and below zero, not a low value cut-off. Negative input values are possible from the source tag and are totaled as such.
Engineering Units
Text stating what the Totalizer tag is totaling (e.g. Gallons, Liters…).
External Reset
Specify a tag or calculation to force a reset of the totalizer. Note that the current value of the tag will always be logged before a reset. The reset will occur when this input changes from a 0 or false value to a non-zero value. A change from invalid to non-zero does not cause a reset.
Update Interval (Seconds)
Controls the frequency of calculations. The value cannot be set lower than 1 second.
To reduce the load on your system, set the largest update interval that still provides the information you need.
Totalizer properties Merit tab
Use the Questionable Data parameter to flag this tag’s data in the event that you suspect the values it is reporting might not be accurate, or when this tag has initially been created and you wish to ensure that its data is marked for extra monitoring.
Privilege
Select a custom security privilege
Totalizer properties Historian tab
Historian
If an Historian tag is selected, this tag's run-time values will be saved for use in reports and the Historical Data Viewer. Historian configuration and advanced logging options are described in the discussion of the Historian Tags.
If your goal is to disable logging, set the Enable parameter (below) to 0 rather than deleting the Historian parameter.
There are consequences if you change the selected Historian tag after you have begun collecting data. If you switch to a new Historian (perhaps for organizational or load sharing purposes), the data collected for this tag by the previous Historian will become inaccessible. Historian selection and configuration should be done during the project design stage.
Totalizer tag properties: Display tab
When this tag is represented on screen by widgets that can use a Style Settings tag, you can save development time by choosing the Style Settings tag that holds the correct display configuration for this tag instance.
The default configuration will use System Style, the default style tag that is automatically part of every new VTScada application.
Totalizer Tag Widgets
The following widgets are available to display information about your application’s Totalizer tags:
