This chapter describes online trend configuration.
Overview of Trends
A trend is a pre-built display object, configured in FoxDraw, which shows continuously changing data within a graph area. The data, which appears as a polyline within the graph, moves across the display from the right side to the left side.
A trend can:
Display up to four independent process variables (points in the control system)
Display a label/description next to the trend line
Show a variable amount of data, based on the trend’s duration and scan rate
Take one of two presentation formats (merged or banded)
Be configured to display different scales (min/max, max/decades, Boolean labels)
Be temporarily or permanently modified.
Online Trend Configuration
Online trend configuration allows you to change the contents and general appearance of a time-based trend after it has been called into FoxView.
Real-Time and Historical Trends
Trend areas display data (trends) representing changing data values from the real-time and historical databases.
Real-time trend areas are continuously updating trend graphs, displaying the most recent trend variable data. Optionally, historical data from the AIM*Historian can also be displayed within the trend.
Trend data displays as a series of plotted points connected by straight lines. Scaling of the data on the vertical axis is according to:
High-scale and low-scale limits configured for each trend line
Auto-scaling
Stored control processor (CP) values
Current limits.
Real-time trend data scrolls to the left as new trend data displays on the right. New data displays at the configured scan rate.
Trend Duration and Scan Rate
You can configure the graph area attributes that control the trend duration and scan rate.
Values for duration and scan rate are entered via the Data Rate Selection dialog box. If the duration and scan rate values conflict, the Valid Scan Rates dialog box presents one or more valid scan rates from which to select.
To improve the speed with which changes in the field are reflected in the Trend, use the Fast Scan option in FoxDraw. Select Display Properties from the FoxDraw File menu and click the
OM_Data tab in the Display Properties dialog box. The dialog box also allows you to set a Scan Rate and Scan Delay.
Duration and Scan Rate Rules
The values for duration and scan rate rely on each other. If the scan rate changes, a new duration is computed. Conversely, if the duration changes, a new scan rate is computed. The values for duration and scan rate follow these rules:
The default value for duration is 15 minutes.
The default value for scan rate is 3 seconds.
The scan rate value has a minimum of one second (corresponding to a minimum duration of 60 seconds) and may change in minimum increments of whole seconds.
The ratio of duration to scan rate must be less than or equal to 600:1.
Trend Line Auto-Scaling
FoxView can automatically scale a trend. The use of this scaling method continually resets a pen’s minimum and maximum scale values, based on the current data points being displayed. The resulting trend provides maximum resolution.
How FoxView Auto-Scales a Trend
FoxView performs auto-scaling in two ways: by enlarging the scales and by shrinking the scales.
As points are plotted, minimum and maximum scales are checked to determine whether new points fall outside of the current minimum and maximum.
If points fall outside these limits, FoxView enlarges the scale to accommodate the points and redraws the trend.
If all the points lie inside the scales (such that the scale minimum value would increase or the scale maximum value would decrease), FoxView shrinks the scale and redraws the trend. Scales are rounded up to the next whole number for maximum scale and rounded down to the next whole number for minimum scale.
When rescaling of trend lines occurs, a minimum span value is configured as a percentage of the Duration The length of the period that is displayed on the trend.
Scan Rate The time between plotted points.
Online Trend Configuration
Online trend configuration allows you to change the contents and general appearance of a time-based trend after it has been called into FoxView.
Capabilities
Online trend configuration capabilities allow you to:
Assign a process variable to a trend pen
Delete a pen from a trend
Change a trend’s duration and scan rate
Configure trend presentation (merged/banded, off-normal regions, grids, markers, colors, time stamp format, and pen data type)
Select how a pen’s scale values are to be configured
Add static lines at user-defined values
Specify the number of decimal places a trend displays.
Save configuration changes.
Boolean Pens
Pens configured in FoxDraw to be Boolean, and which are not modified within the Online Trend Configurator, display as Boolean pens within FoxView.
NOTE
Logarithmic trends do not support the Boolean pen type.
Permission to Configure an Online Trend
Various features of the Online Trend Configurator may be protected from unauthorized use.
Specific protection prevents unauthorized persons access from:
Accessing the Online Trend Configurator (TND_PROT).
Using the keyboard to specify the process variable or description for a trend pen (TLC_PROT, TLD_PROT).
Permanently saving online trend configuration changes (PSV_PROT).
Refer to Display Manager Commands (B0193DF) for details.
Saving an Online Trend Configuration
If you have access to the Online Trend Configuration dialog box’s Permanent button, after modifying a trend configuration, clicking this button saves the original trend display file.
Access to the Permanent button may be denied based on the type of display that contains the trend being configured or based on the security settings of the current environment.
The Permanent button is disabled when:
The current user does not have permission to make permanent changes
The trend is in a Detail Display
The trend is in a display that had been converted on invocation from a Display Manager packed display file (.pdf ) to FoxView display file (.fdf )
The trend is in a display that cannot be optimized.
Trend Presentation
A trend can be configured to:
Be merged or banded
Trend pen lines and markers
Include off-normal areas
Display grid lines
Display static lines
Use a local or regional time stamp.
In addition, you can configure a trend’s data rate and scales.
Select and Assign Capability
Use FoxView’s select point mode to select a process variable by picking an updating numeric graphic object (such as a tank level or moving marker) on a display. This capability allows you to assign an object’s connection variable to a trend line without using a keyboard.
For example, when you are in select point mode and you pick an updating tank, the tank level connection is selected and the connection variable is available for assignment to a trend line.
When selecting an updating graphic object with the right mouse button to copy the connected variable to the clipboard, all process variables that are connected to the object get displayed in the selection menu. For example, the process variables for both the Fill level and Fill color connec-tions are displayed in the pop-up menu. Either menu item may be selected. Connected variables are often copied to the clipboard so they can be assigned to a trend pen.
NOTE
Some process variables are not appropriate for trending. For example, although .BLKSTA and .ALMSTA are parameters that are often used in process graphics, these parameters are bit strings and cannot be trended without specifying the bits to
Keyboardless Assignment of a Selected Object to a Trend Line
Keyboardless (mouse-based or pointer-based) assignment of a selected object connection variable to a trend line is performed using a ScratchPad or non-ScratchPad display, in conjunction with FoxView’s Select and Assign capability.
Before assigning the selected object connection variable to a trend line, note that:
The assignment of Boolean data (packed Boolean or packed long parameters) is supported only in part by the Select and Assign function. If a Boolean data type is assigned, the trend line displays the data (0 or 1) as a numeric trend line, with a range of 0 to 100. The data type can be changed only within FoxDraw, not within the Online Trend Configurator.
The FoxView with the source connection need not be the same as the FoxView with the destination trend area; however, the two FoxView applications must display on the same screen of a single-head configuration, or on either head of a multi-head
configuration. The Select and Assign capability does not work across multiple desktops. Both FoxView and Display Manager can be used interchangeably as the source or the destination.
Once a selected point is assigned (retrieved), the selection is cleared and the selection process must be repeated if the point is to be assigned to another trend line.
The newly trended point acquires default parameters (such as ranges and engineering units) from the Control Processor’s database. You must access the Online Trend Configurator to modify these default values.
The AIM*Historian instance for the selected point is automatically found.
Trend Scales Configuration
The scales you configure for the trend depend on whether the trend is linear or logarithmic.
Linear Trends
A linear trend allows you four ways to configure the maximum and minimum values.
Auto-scale FoxView uses auto-scaling for the pen.
CP Values FoxView uses the values stored with the Control Processor (CP).
User Entered Allows you to enter the minimum and maximum values for the scale. You can type in the Max and Min fields, or use the zooming buttons and arrow buttons to adjust the range.
Use Current Limits Sets the scales based on the trend data currently displaying in the online trend. This button provides a one shot capture capability that reads the current maximum and minimum values of the data points in the display and sets the scale range based only on their data values.
Logarithmic Trends
A logarithmic trend that uses Boolean data allows you to configure a state 0 name and a state 1 name.
A logarithmic trend that uses numeric data allows you to configure these items:
Numeric Data
Whether the trend is linear or logarithmic, for numeric data, you can specify:
Online Trend Configuration Session
If you have the proper permission (access levels), you can configure a trend and view it immediately. If you have the proper permission, you can also create and save a new trend configuration, which overwrites the current configuration and is automatically launched in subsequent applications of the trend.
NOTE
If a display contains more than one trend, each trend is permanently saved indepen-dently. Saving one trend does not affect the configuration of other trends.
During an online configuration session, FoxView continues to update without interruption. All actions can still be taken from within FoxView. If the display being configured is dismissed, the Online Trend Configurator is also dismissed.
Only one Online Trend Configurator session is allowed at a time for each FoxView.
Configuration Session Tasks
An online trend configuration session includes these tasks:
Selection of a process variable (point) for trending.
Selection of a trend to which to assign the process variable.
Assignment of the process variable to a particular trend pen.
Configuration of the trend, including:
Max The maximum scale value.
Low Decade The number of the low decade, which is equal to the exponent.
Delta The deadband.
Engineering Units The engineering units.
Guard Band The additional range or buffer added to the calculated range when FoxView determines the range for an auto-scaled pen.
Minimum Span The absolute range between the minimum and maximum values set by auto-scale. For example, if Minimum Span is set to 5.0, this is the minimum range for the pen.
Windows and Dialog Boxes
Online Trend Configuration Dialog Box
This dialog box includes these portions:
Figure 8-1. Online Trend Configuration Dialog Box
Title (top) Station name, FoxView name, and window title.
Left side Pen’s process variable, description, and fields for selecting a pen for configuration or deletion.
Right side Available fields and buttons depend on whether the trend is linear or logarithmic.
Advanced Graph Tab
Use the Advanced graph tab of the Advanced Trend Configuration dialog box to configure the selected trend. Table 8-1 describes the Advanced Graph tab options.
Table 8-1. Advanced Graph Tab Options
Item Description
Data Rates Group Box
Select Invokes the Data Rate Selection dialog box from which to specify duration and scan rate.
Duration Displays the size of the time period that the trend will display. A short time period displays dat1.a points more frequently.
Scan Rate Displays the time between plotting points.
Off-Normal Group Box
High-Limit Specifies the off-normal operating area at the top of the graph.
Low-Limit Specifies the off-normal operating area at the bottom of the graph.
Gridline Visibility
Visible Displays grid lines by default.
Number of Divisions Field for selecting the number of grid lines for the trend. The default is ten.
Y–Axis Scale
Use Same Scale Activates the three fields associated with this group of settings. This setting allows FoxView to display multi-pen graphs.
Scale Increment Set the increments for display between the low and high scale.
Low Scale Sets the lower bound for display.
High Scale Sets the upper bound for display.
Format
Decimal Digit Specifies the number of decimal places a trend displays. The range is from -1 to 4.
Line-Style
Marker Specifies whether to use markers to display plotted lines.
Markers Per Line Specifies the number of markers to display per line.
Markers Every Point Displays a marker on each plot point. When you do not select this option, a marker is placed on the most recent point only.
Graph Attributes (Bottom of Dialog Box)
Graph Color Specifies the trend area’s background color.
Off-Normal Color Specifies the off-normal operating areas at the top and bottom of the trend graph. These areas, which can be configured in any color, are based on a percent of range for the entire graph.
Grid Line Color Specifies the color for the grid lines. By default, this is gray.
Display Style Merged specifies that up to four trend lines appear in one field. This is the default.
Banded presents four trend lines on four separate, quarter height fields. If there are fewer than four trends, the trend area is divided equally among the trends. Banded format is especially useful for viewing auto-scaled trends.
Saving Options Temporary specifies that the online trend configuration settings be used on a time-based trend after the trend has been called into FoxView. Once the trend is closed or dismissed, the online trend configuration edits are lost.
Permanent specifies that the online trend configuration settings
be used sand saved. After saving permanent changes, calling up a display that contains the modified trend includes changes from the online trend configuration session.
Note: Depending on your workstation’s configuration, you may not be able to permanently save the online trend configuration.
Time Stamp Local specifies a local time stamp.
Relative specifies a relative time stamp.
Reset Reverts to previous settings.
Help Invokes the Online Trend Configurator On-Line Help.
Static Line Settings HI-LO
LO-LO HI-HI LO-HI
Specifies a percentage value and color for each of the status lines. The lines can also be configured in the FoxDraw Grid tab.
Table 8-1. Advanced Graph Tab Options (Continued)
Item Description
Advanced Pen Tab
The Advanced Trend Configuration dialog box offers four Advanced Pen tabs (Table 8-2). Each tab configures one trend pen. For example, Advanced Pen 4 configures pen 4.
NOTE
Depending on the method (linear or logarithmic) used to configure a pen in Fox-Draw, a Pen Scale group box or a Log Scale group box appears within this dialog box. The selection of logarithmic or linear scales is a plot area attribute and, therefore, applies to all lines plotted in the trend.
The data type selection (Numeric or Boolean) determines the available specification boxes.
Table 8-2. Advanced Pen Tab Options
Item Description
Advanced Trend Configuration Dialog Box
Assign button Places the object’s process variable in the Variable box.
Variable box (To the right of the Assign button) Displays the object’s process variable (Compound:Block.Parameter).
Browse Invokes the Advanced Trend Configurator Compound:Block.Parameter browser from which to select a process variable.
Delete Removes the name of a process variable from the Variable box.
Description Displays the description text that appears beside the pen. If you have permission, you can enter text into this box.
Historian Name Displays the name of the AIM*Historian instance from which the specified process variable’s data values are to be obtained. If you have permission, you can enter the instance name or click the down arrow to select the historian.
Show this Scale Check the Y-Axis Scale Visible and Show this Scale for Pen 2 to select Pen 2's scale for use by FoxView and sets the color of the scale to Pen 2's color.
Pen Scale Group Box
Auto FoxView uses auto-scaling for the pen.
CP Values FoxView uses the values stored with the Control Processor (CP).
User Entered Allows you to enter the minimum and maximum values for the scale. You can type in the Max and Min fields, or use the zooming buttons and arrow buttons to adjust the range.
Use Current Limits
Sets the scales based on the trend data currently displaying in the online trend.
This button provides a one shot capture capability that reads the
current maximum and minimum values of the data points in the display and sets the scale range based only on their data values.
Max Enter a maximum value for the pen scale.
This field is available only when User Entered is selected.
Min Enter a minimum value for the pen scale.
This field is available only when User Entered is selected.
Increment Enter an increment value for the pen scale.
This field is available only when User Entered is selected.
Log Scale Group Box
Max If the trend is configured for logarithmic scales, enter the maximum scale value.
Low Decade If the trend is configured for logarithmic scales, enter the number of the low decade. The decade number is equal to the exponent.
Data Type Group Box
Data Type Specifies the data type (Numeric or Boolean).
Numeric enables the Delta, Engineering Units, Guard Band, and Minimum Span boxes.
Boolean enables the State 0 Name and State 1 Name boxes.
Delta Specifies the deadband (for numeric variables only).
This field is enabled only for a Numeric data type.
Engineering Units
Specifies the engineering units (for numeric variable only).
This field is enabled only for a Numeric data type.
Guard Band The additional range or buffer added to the calculated range when FoxView determines the range for an auto-scaled pen. A value appears only when Auto is specified in the Pen Scale group box.
This field is enabled only for a Numeric data type.
Minimum Span Specifies the absolute range between the minimum and maximum values set by auto-scale. For example, if Minimum Span is set to 5.0, this is the minimum range for the pen.
This field is enabled only when Auto is selected.
This field is enabled only for a Numeric data type.
This field is enabled only for a Numeric data type.