In the Property Binder topic, the concept of data binding was introduced. Using data binding it is possible to display values returned from the Exaquantum database on documents. This mechanism provides read only access to the data, however, if values need to be written back to the real time database, one of the following methods can be used.
Values can be entered into the Exaquantum database from Exaquantum/Explorer documents using the Data Entry Grid control. The Data Entry Grid allows a specific set of data to be written but if more flexibility is called for, the Exaquantum/Explorer input controls can be used. In addition values can be written to Exaquantum from script.
Note: To write values to the DCS the appropriate security level must be set on the DCS. For example, in the case of the CS3000, the user role of the 'PROG' should be set to S4 instead of the default S1. For information about procedures relating to DCS security configuration refer to the Reference Manual IM 33S1B30-01E.
On the Palette a set of data input controls are provided that can be connected to Exaquantum/Explorer variables via their respective ValueID properties. Changes made to these controls can be written back to their connected data variables.
EditBox
CheckBox
RadioButton
ListBox
ComboBox
Slider
SpinButton.
Exaquantum/Explorer variables play an important part in the data write-back process. The variables act as the link between the control and the underlying Exaquantum database. When an edit control is connected to a data variable, changes made to the control not only affect the values of the variable itself, but the value is propagated all the way back to the underlying database.
Note: Data controls can also be connected to local variables. Local variables don’t propagate their values beyond the bounds of documents.
The first step to configure Data Write Back is to create the necessary data variables, which can then be connected to controls. The simplest way to create the variables is to put a text control (label) on the document, and to drag tags from the Data Selector onto it. The label may be deleted once all the variables have been created (Refer to Property Binder for the full procedure). Data Write Back can also be used with parameterised variables (Refer to Data Parameterisation - Variables for a full description).
For more information about and example of Data Write Back see IM 36J04A12-01E Exaquantum/Explorer Use's Manual.