Points / Equation List
Introduction
Clicking on the Points / Equation List menu displays the Equation List page.
The following image illustrates the Points / Equation List page after an equation has been selected in the list at the top of the page.
Equation Page (see full-size image)
Equations allow computing data values from one or more sensors and storing the computed values in the database for display, alarm checking and notification. The computed data values are stored in an export point that must be defined in the database. Before defining an equation, it is necessary to first define the export point where the equation result will be stored. See the Point List page.
The export can be assigned to one of the stations whose point is used in the equation computation or define a new station and assign the export point to it. A new equation may need to be created for the equation computation data units. See the Point Type List section.
Equation List
A new NovaStar system will display an empty Equations List.
Equation List (see full-size image)
Click the Add button at the upper right-hand corner of the Equation List table to create a new equation. Or, click the Edit button followed by the Copy button associated with an existing equation to use that equations as a copy template for creating a new equation. New euqations must be given a unique Name.
The points and their data analyses that are used in the equation computation are defined in the equation import list. Equation computations are triggered when a data report is inserted or updated in the database for a point in the equation import list.
Navigation, Adding, Deleting, Modifying, and Copying Equations
See Application Functionality for more information about basic component functionality.
The Equation List page conforms to a layout similar to many data types which includes a list of data items. See List Features for more information detailing page navigation; adding, copying and deleting equations; and modifying existing equations.
Identification
The following properties are used to identify the equation.
Equation Identification (see full-size image)
| Data Label | Description |
|---|---|
| Name | Unique identifier for the equation being created. This is the name that will appear in reports and point pick lists. |
| Description | Additional information describing attributes of the equation. Max: 1000 characters. |
| Export point | Select point for storing the equation computed data values from the pick list. |
| Equation type | Select the equation type from the pick list. Standard: Combine import point data analysis using arithmetic or logical operations. Average: Average import point data analysis data values. Dew point temperature in degrees C: Compute dew point temperature in degrees C from air temperature in degrees C and relative humidity in percent. Dew point temperature in degrees F: Compute dew point temperature in degrees F from air temperature in degrees F and relative humidity in percent. Wet bulb temperature in degrees C: Compute wet bulb temperature in degrees C from air temperature in degrees C and relative humidity in percent. Wet bulb temperature in degrees F: Compute wet bulb temperature in degrees F from air temperature in degrees CFand relative humidity in percent. Vapor pressure from temperature in degrees C: Compute vapor pressure in millibars from air temperature in degrees C and relative humidity in percent. Vapor pressure from temperature in degrees F: Compute vapor pressure in millibars from air temperature in degrees F and relative humidity in percent. Evapotranspiration demand from temperature in degrees C: Compute evapotranspiration demand in millimeters per hour from solar radiation in watts per square meters, air temperature in degrees C, relative humidity in percent, wind speed in kilometers per hour and air pressure in millibars. Evapotranspiration demand from temperature in degrees F: Compute evapotranspiration demand in millimeters per hour from solar radiation in watts per square meters, air temperature in degrees F, relative humidity in percent, wind speed in kilometers per hour and air pressure in millibars. |
| Enabled | Select true to compute and store the equation data values; false will not compute or store the equation data values. |
User Groups
The User groups table shows the user groups currently assigned to the station. For more information, see the User Groups documentation.
User Groups Assigned (see full-size image)
Import List
The points and their data analyses that are used in the equation computation are defined in the equation Import list. When an equation is first defined, no import records will be assigned. The analysis shown in the Import list is a single string representing the combination of options selected in the Equation popup when editing or adding an import.
Import List (see full-size image)
See Sublist Functionality for more information about adding, deleting, and editing sublists.
Import Popup (see full-size image)
| Data Label | Description |
|---|---|
| Import type | Select type of import from pick list. Changing this type will affect the fields shown in the edit panel. Constant: Constant value used in equation. See Equation Import Constant. Point analysis: Result of point data analysis used in equation. See Equation Import Point Analysis. Trigger Only: Data stored for point triggers equation computation but point data not used. See Equation Import Trigger Only. |
| Operation Type | Select type of operation from pick list. Changing this type will affect the fields shown in the edit panel. Arithmetic: Use Equation Import Arithmetic Operations (defined in the Operation row of this table) to modify equation value by point data analysis or constant value. This operation is only executed if conditions met, see the Condition row of this table. Logical: Use Equation Import Logical Tests (defined in the Test row of this table) to compare equation value with point data analysis or constant value. |
| Operation | Select arithmetic operation from pick list. none: No action + add: Add equation running total to point data analysis or constant value. - subtract: Subtract point data analysis or constant value from equation running total. * multiply: Multiply equation running total by point data analysis or constant value. / divide : Divide equation running total by point data analysis or constant value. % modulus: Assign remainder of equation running total divided by point data analysis or constant value. or: Or equation running total with point data analysis or constant value. ^ exclusive: Exclusive or of equation running total with point data analysis or constant value. & and: And equation running total with point data analysis or constant value. << bit shift left: Shift left equation running total by point data analysis or constant value number of bits. >> bit shift right : Shift right equation running total by point data analysis or constant value number of bits. = assign: Assign point data analysis or constant value to equation running total. MAX: Save maximum point data analysis. MIN: Save minimum point data analysis. |
| Condition | Select the logical test results from pick list. none: No action. when false: Perform arithmetic operation when previous logical test was false. when true: Perform arithmetic operation when previous logical test was true. |
| Test | Select logical test from pick list. none: No action. ** == equal: Return true if equation running total is equal to point data analysis or constant value. != not equal: Return true if equation running total is not equal to point data analysis or constant value. < less than: Return true if equation running total is less than point data analysis or constant value. ** <= less than or equal: Return true if equation running total is less than or equal to point data analysis or constant value. > greater than: Return true if equation running total is greater than point data analysis or constant value. >= greater then or equal: Return true if equation running total is greater than or equal to point data analysis or constant value. |
| Point | Select a point to add to the import list from the pick list. |
Equation Import Constant
The Constant import type performs the arithmetic operation or logical test using a constant instead of a point data analysis value.
Import Popup Constant (see full-size image)
Equation Import Point Analysis
The Point analysis import type performs the arithmetic operation or logical test using the point data analysis value. The equation computation is triggered when a data report is filed in the database for the analysis point. The following options are provided. Once all desired options are selected, a single analysis string is created to represent selections and saved as an import definition.
Import Popup (see full-size image)
| Data Label | Description |
|---|---|
| Point | Select point to trigger the equation computatation from the pick list. |
| Analysis | Select the data analysis for the point data. See the data analysis appendix for a description of the analysis types. Use default analysis will do the default analysis for the point type. |
| Analysis Interval | The Storm Rainfall and Rainfall Intensity data analysis require an analysis interval. See the data analysis appendix for a description of the analysis interval use for these analysis types. Click the button to alternate between interval selection from a pick list or from time interval fields. |
| Data type | Select the type of data displayed: Scaled: Scaled or analysis value Raw: Raw data value Score: Nova score value Rating 1 - Rating 5: Rating value 1 - 5 |
| Display Interval | Select the time interval for the data analysis. The time interval is used to compute the start time for the data analysis from the end time. Click the button to alternate between interval selection from a pick list or from time interval fields. Use Request Interval and Show Data Reports will use the point data checking no report interval by default. |
| Time Offset | Select the time offset from the trigger data report time for the data analysis period, default if 0.0 seconds. A positive time offset starts in the future (After), a negative time offset starts in the past (Before). Click the Time Offset: button to select from a list of intervals. The time offset direction is selected from the After/Before list. |
| Multiplier | Multiply the data analysis computed value by this constant. |
| Adder | Add this constant to the data analysis computed value. |
| Post analysis | Select additional arithmetic operation and constant value to be applied to the result of the point data analysis. |
Equation Import Trigger Only
The Trigger only import type does not modify the equation computation. It is used to trigger the equation computation when a data report is filed in the database for the trigger point.
Import Popup (see full-size image)
Equation Examples
Equation Average Computation
The Average equation type computes the average of the equation import values and stores it in the export point.
Equation Average Computation Example(see full-size image)
Equation Rating Computation
This Standard equation type computes the rating value of the import point and stores it in the export point.
Equation Standard Computation Example(see full-size image)
Equation Dewpoint Temperature Computation
This Dew point temperature in degrees F equation type computes the dew point temperature from the temperature and relative humidity import points and stores it in the export point.
Equation Dewpoint Temperature Example(see full-size image)
Equation Evapotranspiration Demand Computation
This Evapotranspiration demand from temperature in degrees F equation type computes the evapotranspiration demand in inches from the solar radiation, temperature, relative humidity, wind speed, and barometric pressure import points and stores it in the export point.
Equation Evapotranspiration Demand Example(see full-size image)
Equation Barometric Pressure in Inches of Mecury Computation
This Standard equation type computes the barometric pressure in inches of Mercury from the barometric pressure import point in millibars and stores it in the export point.
Equation Barometric Pressure in Mercury Example(see full-size image)
Equation Maximum Computation
This Standard equation type computes the maximum value from import point values and stores it in the export point.
Equation Maximum Example(see full-size image)
Equation Composite Water Level Computation
This Standard equation type computes the composite water level from two import point water level values and stores it in the export point. If the water level from the 40 inches PT is greater than 175 feet, then assign the 40 inches PT water level value to the export point. If the water level is at or below 175 feet, assign the 10 feet PT water level value to the export point.
Equation Water Level Example (see full-size image)
Equation Delete
To delete a equation from the Equation List, select the equation in the Equation List and then click Delete. The page prompts to click the Delete button again to confirm that the equation should be deleted. Deleting an equation does not delete the export point. Delete the point first using the Point List page.