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Chapter 6 Monitors

5. Text Update Objects

Even though the option in the monitors' submenu says text, text monitors are known as text update monitors, and they are labeled as such in EDD. Text update monitors are different from the other monitors--indicators, bars, and meters -- in several ways.

They have no display limits, so the 'high and low display limit' properties in a text update's property sheet are meaningless.

They are the only type of monitor that displays the precise numerical value of their channel. The other monitor objects display the value graphically within a range, the limits of the range being displayed numerically if configured to do so. For example, if a channel that an indicator is monitoring is 55 and its display limits are 0 and 100, the indicator doesn't display 55, but instead places the indicator at a position which is a little to the right of the halfway mark. A text update object, on the other hand, will display 55.

The 'label type' property is also meaningless for text update objects: text update objects can only display two things: the value of the channel that they are monitoring and the text string from the EGU field of the same record.

The text update monitor is the only type of monitor that uses the units modifier property, which when set to append retrieves the string from the EGU field of the record that the object is monitoring. The other types of monitors have this property, but it is meaningless for them.

The text update monitor is the only monitor that can display non-numerical values, such as NO_ALARM for the SEVR field.

Figure 6-12 shows the property sheet of a text update object.

The 'units modifier' property is a choice button, the choices being none and append. When set to append (left-click on append), at run-time the string in the EGU field is retrieved and appended to the displayed value of the channel that the text update is monitoring. Usually, EGU is a text string, like volts or ohms.

The 'text alignment' property determines where to display the information the text update object displays. There are six settings:

1. horiz. left (horizontal left)

2. horiz. right

3. horiz. centered

4. vert. top (vertical top)

5. vert. bottom

6. vert. centered.

Text Update Property Sheet .

The three horizontal settings arrange the information horizontally, from left to right at run-time. The vertical settings arrange the information vertically, from top to bottom. The horizontal left setting aligns the leftmost character of the value string with the object's left edge; the horizontal right setting aligns the rightmost character of the value string with the object's right edge. The horizontal centered setting centers the value between the left and right edges. The horizontal settings always center the value vertically, between the top and bottom edges. Figure 6-13 shows the run-time appearance for each horizontal alignment setting.

Horizontal Alignment Settings for Text Updates

The vertical top setting aligns the first character of the value string with the object's top edge; the vertical top setting aligns the value string with the object's bottom edge. And the vertical centered setting centers the object vertically, between the top and bottom edges.

Vertical Alignment Settings for Text Updates

When the text alignment is horizontal, you must be sure that the object's horizontal size is sufficient to display the value string of the channel that the object is monitoring, especially if that string happens to be a long one because horizontal text is 'cut off' if it is too long to fit in the object. In a vertically aligned object if the value string is too long for the first column, it will carry over to the second, and if too long for the second, to the third; and so on until the object cannot fit any more columns due to its size. The similarities between the text arrangement in EDD and the run-time appearance of the value string in a text update object will help you anticipate the appearance of the text update object at run-time.

The final property in the text update's property sheet that we will discuss is the 'text format' property. It has six settings that determine how numerical values are displayed:

7. decimal

8. decimal -exponential notation

9. decimal -compact notation

10. decimal -truncated notation

11. hexadecimal

12. octal

The first three settings all use the 'precision' property to determine the decimal precision with which to display the value, unless the precision property is less than 0, in which case the precision is retrieved from the database, usually from the PREC field. The decimal option displays the value in normal decimal format. Decimal -exponential notation displays the value in exponential notation. For example, if the value of the channel is 535.6978 and PREC is two, the text update object will display 5.35e+02. The decimal -compact notation setting also uses PREC to determine the number of digits to be displayed. It uses the C language's %G notation, so C will determine which format of the other five formats to use. Usually, it will use decimal -exponential notation for large numbers and ordinary decimal notation for smaller numbers.

Decimal -truncated notation basically displays the value without decimals. It does not round the number, just chops it off at the decimal point, displaying only the integral number. So with this setting if the channel's value is 524.987, the text update object will display 524, not 525. The hexadecimal setting displays the value of the channel in integer 16-based notation (1-9,A-F); and the octal setting displays the channel's value in integer eight-based notation.

EDD/DM User's Manual, 2.4 - 27 MARCH 1997
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