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Chapter 7 Controllers

2. Valuators

Valuators are used at run-time to change the values of channels with a mouse. They will work with any type of channel that returns its value as a numeric value, be they analog or discrete channels; yet they are designed primarily for use with analog channels. At run-time, valuators work like the sliders encountered in EDD property sheets, the color table, and the Display Attributes window.

At run-time, a valuator has a triangular pointer that the operator moves or "slides" by dragging the mouse, changing the value of its channel. In addition, as of 2.4, the user can control the valuator at run-time using the keyboard's arrow keys. The various configuration options and settings in a valuator's property sheet mainly affect its appearance.

A Valuator's Property Sheet

There are four settings for the 'label type' property: none, outline, limits, and channel. When none is selected, only the valuator's pointer is displayed at run-time; when outline, the pointer and ruler markings are displayed. When either limits or channel is selected, the pointer, ruler markings, and operating limits are displayed. Figure 7-4 shows two possible run-time appearances of valuators with different 'label type' settings.

Label Type Settings (run-time appearance).

The 'high and low display limit' properties determine the range of values that a valuator can send. The two values on either side of the middle value in Figure 7-4 are the low and high display limits. A valuator can only change the value of the channel within the range of the high and low display limits, so by setting these limits you restrict the values to which the operator can change the channel's value at run-time. In Figure 7-4, for instance, the operator could not change the value of the channel to less than zero, nor to more than a 100. In addition, the high and low display limits restrict the displayed value to a value in its range, so the channel's value could be -15 in Figure 7-4, but the valuator's value would show zero.

If both the 'high and low display limit' properties are set to zero, DM will retrieve the high and low display limits from the database. Where these limits come from depends on the record and the field. For many analog records, there are drive limits specified in two fields (DRVH and DRVL, usually) that control how small or large the value can be. The display limits set in these properties override the limit fields in the database.

The 'pointer direction' property has four settings that determine towards which direction the valuator's pointer points and whether the valuator is situated horizontally or vertically. The up and down settings situate the valuator horizontally, the right and left settings, vertically. With the up setting, the direction of the pointer is up; with the down setting, the direction is down. With the right setting, right, and with the left setting, left. Figure 7-5 shows the run-time appearance of each setting.

The 'gain,' 'send value mode,' and 'decr amount' properties have not been implemented as of EDD 2.3.

Pointer Direction Settings

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