The active display of the TPRI.ToggleButton object consists of two main states: on (true, non-zero) and off (false, zero).  The display of each of these states is configured by setting the various object properties.

When the button is pressed, the current value of the associated global common variable is changed to the opposite state. For example, if the variable is currently true, its value is changed to false and vice-versa. The button is then disabled until the new variable value is updated back to the screen. This prevents accidental double clicks of the button from changing the variable back to its original value.

In general, the bar graph is configured according to the following.  

Number of bars

The horizontal extent of the display is divided into N bar slots, where N is equal to the tNumBars property.  Each of the bar slots is divided into a left and right bar; when active, the heights of each of the left bars correspond to the values in the first (right) array, while the heights of each of the right bars correspond to the values in the second (left) array.

Alternatively, the tNumBars property can be set to the name of a variable in global common.  In this case, the bar graph will retrieve the value of this variable and use it to configure the number of bars displayed.  

Horizontal display configuration

Both sets of bars can be configured to take up some fraction of each bar slot.  The property tLeftBarPercent specifies the percentage of each bar slot that the left bar should consume; the left bar is always assumed to start at the leftmost edge of the bar slot.  The property tRightBarPercent specifies the percentage of the bar slot that the right bar should consume; however, the starting point of the right bar is specified with the tRightBarOffset property.  If the sum of tRightBarOffset and tRightBarPercent exceeds 100, the right bar will be truncated as the rightmost edge of the bar slot.

Vertical display configuration

The displayed heights of each bar are specified relative to three TPRI.BarGraph properties.  The tEngUnitCenterLine property specifies the engineering units of the horizontal centerline of the graph.  This is line from which each of the bars will grow up or down.  If the array element value associated with a given bar is less than tEngUnitCenterLine, the bar will be drawn down from the centerline, and conversely, if the value associated with a bar is higher than tEngUnitCenterLine, the bar will be drawn up from the centerline.  This allows the bar graph to be configured to display deviations from a nominal non-zero value.  The top and bottom vertical limits of the graph are specified by the tEngUnitTop and tEndUnitBottom properties; array element values outside this range will display bars extending to the limits of the display.

If forcing any of these three properties to a fixed value is not appropriate for the display, there are two alternatives.  First, the property can be set to the name of a variable in global common whose value will be retrieved at runtime and used as the associate engineering value.  This allows the display to be programmatically controlled by values in global common.  Second, the property can be set to a special string consisting of an ampersand '@' followed by the name of a text box on the screen; in this case the value entered into the text box will be used as the associate engineering value.  This allows the HMI user to configure the display at runtime as he pleases.

Scale display configuration

The property YTickSpacing is defined as the spacing (in engineering units) between the y-axis ticks annotating the graph.  A tick is a short horizontal line drawn to the left of the graph together with a label indicating the corresponding y-axis position.  A property YTickSpacing value less than or equal to zero indicates that no ticks should be drawn.  A positive value indicates that ticks and labels should be drawn at integer multiples of the spacing value between the lower and upper limits of the graph.  The default value is zero.

In most cases, all operation of the TPRI.OpcMgr object is fully automated by the TPRI.BaseScreen framework. While connected to the data host, the OpcMgr object will display green and indicate the date/time of the most recent variable update from the host.  Before the initial connection and any time the OpcMgr object disconnects from the host, the display will turn orange and will indicate the date/time of the most recent connection attempt; the OpcMgr object should attempt to reconnect every 3-5 seconds.  Finally, there are two cases in which the OpcMgr object will turn red:

If the OpcMgr object is unable to find any variables configured on the screen for retrieval from the server, the object will turn red and display a message indicating that there are no OPC items configured.

If the OpcMgr object encounters an unrecoverable error the object will turn red and display an error indication.  Details of the error can be viewed by holding down the control key and left clicking on the object.

There are some situations where a screen may want to receive variable updates for data that it wishes to use for its own purposes rather than for display in one of the existing active objects.  To accomplish this, the screen should do the following:

Add an event handler for OnRestart(..).  Inside this handler make appropriate calls to the AutoAddItem() method to add all variables that the screen would like to receive directly.

Add an event handler for OnDataUpdate(..).  Inside this handler process individual variable updates.

Optionally add an event handler for OnDisconnect(..).  Place any code to reset the visual display of the screen to indicate that the screen is not connected to the data host.

The TPRI.OpcCom object is an OPC communications client for accessing variables in global common on the host.  

There are no properties exposed by the TPRI.OpcCom class for public use.

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A rule can be saved to a file on disk and stored for later reference by choosing either of the first two save options from the popup menu.  The Save Rule option simply saves the rule to its current file, while the Save Rule As... option saves the rule under a different name or into a different folder.

Before the rule can be saved to disk, though, it must be validated to ensure that each of its parameters is formatted correctly and contains valid data.  If validation is not successful the user will be prompted with a list of problems and the rule display will be populated with a red Local Errors node that contains a duplicate of this list.

For instance, an improperly formatted VariableCondition statement containing unmatched parentheses causes a fatal validation error because the condition cannot be properly parsed.  On the other hand, a properly formatted VariableCondition statement that contains a variable name that cannot be located in the data dictionary only causes a non-fatal validation warning, as this rule can still be properly parsed by the rules manager process.

If only validation warnings are encountered, and there are no fatal validation errors, the user has the option of continuing with the save process or canceling the save to fix the problems; however, if any fatal errors are encountered the save cannot continue.

If a rule is currently active on the host, it can only be saved to the host share under its current name by re-activating it at the same time (see below).  The user may however choose to save the rule to a different folder under the same name.