CIMPLICITY2.2.4. Data Item: Additional Expression Examples
- Example: Alarm Enable
- Example:
$DATA_ITEM_EXISTS
Example: Alarm Enable
Note: When the enable state fields are included for a data item, an object designer can enable/disable the included alarm levels for each object.
The instantiated analog point for a data item named LEVELEXP requires:
- Four alarm states for some objects.
- Alarm High and Alarm Low states only for other object.
| A | Class: Data item configuration. |
| B | Object: Object defined. |
| C | Instantiation: Point properties result. |
- Class: Data Item Configuration
Two analog attributes are created that will display as fields in the Object dialog box.
The attributes are as follows.
| Field ID | Field Name for Attribute Dialog Box | |
| A | $WARNING_HIGH_ENABLED | WARN HIGH ON |
| B | $WARNING_LOW_ENABLED | WARN LOW ON |
Field ID's are assigned to the LEVELEXP data item.
| Field ID | Expression Example | |
| A | $WARNING_HIGH_ENABLED | WARNHIGHON analog attribute. |
| B | $WARNING_LOW_ENABLED | WARNLOWON analog attribute. |
- Object: Object Defined
Two objects are defined in the TANKV class.
STATION05
One object, STATION05, requires all alarm states.
A value that is greater than 0 is required to enable the alarm states.
1 is entered for each
STATION04
One object, STATION04, requires only the Alarm High and Alarm Low alarm states.
The value 0 is required to disable the alarm states.
0 is entered for each
- Instantiation: Point Properties Result
The alarm state values for the instantiated points reflect the entries in the Object dialog box.
STATION05
STATION05.LEVELEXP has four enabled alarm states.
STATION04
STATION04.LEVELEXP has Alarm High and Alarm Low only enabled.
A data item can be included or excluded from being instantiated into a point based on the expression in an assigned $DATA_ITEM_EXISTS field ID.
Example: $DATA_ITEM_EXISTS
A class includes data items, that will be instantiated into points based on which control valve is selected for an object.
The data items require the following control valves.
| Data Item | CVALVE01 | CVALVE02 | CVALVE03 |
| TANK01 | X | ||
| TANK02 | X | ||
| TANK03 | X |
One data item will be instantiated into a point for each object; the data item that is instantiated depends on which valve is selected for that object.
| A | Class: Data item configuration. |
| B | Object: Object defined. |
| C | Instantiation: Point properties result. |
- Class: Data Item Configuration
In the class configuration data items will be assigned to the same attribute.
Attribute Created
An analog attribute, CVALVE, is created that will be used to identify the Valve that should be selected for each data item.
Data Item Configuration
Three TANK data items are created.
The first data item, TANK01 is assigned $DATA_ITEM_EXISTS, with the following expression to associated Control Valve 1 with TANK01.
| Field | Example Value Assigned | |
| First operand | Attribute ID | CVALVE |
| Operator | = | |
| Second operand | Number | 1 |
Two additional data items are assigned the field ID, $DATA_ITEM_EXISTS.
The three data items and expressions for $DATA_ITEM_EXISTS are as follows.
| Data Item | $DATA_ITEM_EXISTS Expression |
| TANK01 | CVALVE=1 |
| TANK02 | CVALVE=2 |
| TANK03 | CVALVE=3 |
- Object: Object Defined
2 is entered in the CONTROL VALVE field for an object, STATION02.
- Instantiation: TANK Points Existing
TANK02 is instantiated for the STATION01 object.
TANK01 and TANK03 do not exist for that object.
