Switching logic provides a convenient means to implement a point's digital (Boolean) logic control. An analog or digital point is commanded to a specific value or state if certain conditions are met. Time delays can also be added. For example, switching logic can start a return air fan 30 seconds after a supply air fan starts.
Function |
The Switching logic module sets the value of the TRUE(1) or FALSE(0) input to the output depending on the defined logic. Switch Cases can be defined for the HVAC system (e.g. Fire or Frost). In the Switching Logic / Rows section, logic operations have to be created that are relevant for the Switch Cases. A logic operation is the comparison of an Actual Value with a Comparison Value using the defined condition. For the Switch cases, it can be determined which logic operation is relevant. If all these logic operations are TRUE (AND relation), the Switching Table becomes TRUE and the TRUE(1) input value is set as output value of the Switching Table. If none of the Switch Cases results to TRUE (OR relation), the FALSE(0) input value is set as output value. |
I/O Dialog Box |
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Input |
Two fixed inputs, containing the FALSE(0) and TRUE(1) values. Two through thirty two input blocks, each representing one row, where:
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Output |
One output (out). The output is set to one of the inputs FALSE(0) or TRUE(1) depending on the result of the switching logic (TRUE or FALSE). |
A Switching Table contains the following sections:
Switch Cases / Columns
Output Value Definition
Switching Logic / Rows
Allows you to add a delay for the switching logic table. For example, if a switching table commands a supply fan when conditions are met, you can add a delay of 30 seconds before the software issues the command.
Note:
The Switch Cases have an OR relation to each other.
Switch Case |
Displays the switch column's name. |
Delay Type |
Displays delay types. It includes On, Off, and Cycle (On/Off). |
Delay |
Displays the delay time of the Switch case validity. |
Delay Unit |
Displays the delay unit (Hours / Minutes / Seconds / Milliseconds) |
Export and Reset column widths |
Allows you to export the table to oBix / PDF / HTML / Text/ CSV. You can reset the column width by clicking the Reset Column Widths option. |
Add Case |
Adds a new case. |
Delete Row |
Deletes the selected case in the table. |
Procedure
1) Click Add Case.
2) In the switch cases table, double-click on the newly added case. The edit case dialog box displays.
3) Enter the case name as required.
4) Select the Delay Type (On / Off / Cycle (On/Off)) by clicking the drop-down option.
5) Enter the Delay Value as required.
6) Select the Delay Unit (Hours / Minutes / Seconds / Milliseconds) by clicking the drop-down option.
7) Click OK. The configured entries will be displayed on the switch cases table.
1) In the Switch Cases table, select an existing case.
2) Click Delete Case.
Displays the definition of the output.
The definition of the outputs are described below.
TRUE Value |
Setup of input TRUE(1) (connection, Datapoint Property etc.) |
FALSE Value |
Setup of input FALSE(0) (connection, Datapoint Property etc.) |
Output |
Setup of output (connection, Datapoint Property etc.) |
Output Delay |
Time delay of the output validity |
Allows you to add a delay for different row conditions. Select output points and specify conditions that software should check to determine whether or not to initiate a change to the output point.
Each input rows consists of the following columns:
Type |
The switch logic type (Numeric or Boolean, or Enum) |
Input Name |
Name of the row. |
Actual Value |
The value that should be compared. |
Case |
Every selected Switch Case is displayed in the Switching logic list-box. For each Switch Case, it can be decided which row have to be TRUE (1), FALSE (0) or don't care (-) to make the case become TRUE. |
Condition |
Relation between the Actual and Comparison values.
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Comparison Value |
A reference value. |
Hysteresis |
A dead-band between Actual and Comparison values. |
Delay Type |
Delay types are On, Off, and Cycle (On/Off). |
Delay |
Delay time of the Switch row validity. |
Delay Unit |
The delay unit (Hours / Minutes / Seconds / Milliseconds). |
Note:
The switching rows have an AND relation to each other.
Procedure
1) Click Add Row.
2) In the Switching Logic / Rows table, double-click on the newly added ow. The
Edit Logic Row dialog box displays.
3) Enter the row name as required.
4) Select the Actual Value (Constant or Connection) by clicking the drop-down option.
5) Select the Condition as required.
6) Select the Comparison Value (Constant or Connection) by clicking the drop-down option.
7) Select the Hysteresis (Constant or Connection) by clicking the drop-down option.
8) Select the Delay Type (On / Off / Cycle (On/Off)) by clicking the drop-down option.
9) Enter the Delay Value as required.
10) Select the Delay Unit ( Hours / Minutes / Seconds / Milliseconds) by clicking the drop-down option.
11) Click OK. The configured entries will be displayed on the switching row table.
1) In the Switching Logic/ Rows table, select an existing row.
2) Click Delete Row.