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Value type selection of the eval tag. Admissible value types are listed in the following table.
| Identification | Eval tag value type |
|---|---|
| De | Logical value |
| Ce | Integer value |
| Ae | Analog value |
| TmA | Absolute Time |
| TmR | Time interval - relative time |
Technical units
Technical units of the eval tag. Maximum: 12 characters. Possibility to use the Dictionary (to open press CTRL+L).
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Technological limits may be defined for eval tags of the Ce - integer, Ae - analog and TmR - time interval type. There are four limits: VHL, HL, LL and VLL. Limit may be specified either directly - by entering a value into the input field, or its value may be defined by a system object (dynamic limit) - the button placed right from the input field.
| VHL | Very High Limit - the highest limit |
| HL | High Limit - high limit |
| LL | Low Limit - low limit |
| VLL | Very Low Limit - the lowest limit |
Values of individual limits determine the state of the eval tag according to the value. The relation eval tag value - limits gives 6 possible states.
| Limit | Object state according to relation Value- Limit |
|---|
| Above VHL (object value > VHL) | |
| VHL |
| Above HL (HL < object value < VHL) | |
| HL |
| Normal (LL < object value < HL) |
| LL |
| Bellow LL (VLL < object value < LL) | |
| VLL |
| Bellow VLL (object value < VLL) |
As the limits can be dynamic (determined by the object value), a situation may occur, when the condition VLL<LL<HL<VHL is not met (the limits crossing). The eval tag is then in the state Limit Problem.
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Time delay (in seconds) for the evaluation of process alarm. Process alarm is raised, if a cause of raising the alarm is valid at least within this period.
Note: the time delay is applied only to status alarms - transition alarms occur immediately when the value is changed.
Block alarms
Enabled Block Alarm option blocks the evaluation of process alarms.
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Example:
Structured variable SV.Production consists of 10 rows and 3 columns.
| Column | Type | Meaning |
|---|---|---|
| ProductsALL | Int | Number of products |
| Rejects | Int | Number of rejects |
| ProductsOK | Int | Number of good-quality products |
Obviously the following equation can be formed:
ProductsOK = ProductsALL - Rejects
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Time offset of the basic time interval (hour:min:sec). It is defined only for the periodical evaluation method of the eval tag.
Use monotonic time
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Maximum density of evaluation [s]
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