12.1.5 Command Expressions and Condition
- Jessica Reyes (Unlicensed)
- Scott Fredericks (Unlicensed)
Under certain circumstances, it may be necessary to use a simple script during the object configuration. For example, you may enter a condition and a command expression to the touch object as shown below. The conditional and command expressions follow the format of script programming.
(1) Condition Expression
Operator | Function | Example | Description |
&& | Logical AND | A && B | If A and B are true, the result is 1. In other cases, the result is 0. |
|| | Logical OR | A || B | If A and B are false, the result is 0. In other cases, the result is 1. |
< | Less than | A < B | If A is smaller than B, the result is 1. In other cases, the result is 0. |
> | Greater than | A > B | If A is greater than B, the result is 1. In other cases, the result is 0. |
<= or =< | Less than or equal to | A <= B | If A is smaller than or equal to B, the result is 1. In other cases, the result is 0. |
>= or => | Greater than or equal to | A >= B | If A is greater than or equal to B, the result is 1. In other cases, the result is 0. |
== | Equal to | A == B | If A is equal to B, the result is 1. In other cases, the result is 0. |
!= | Is not equal to | A != B | If A is not B, the result is 1. In other cases, the result is 0. |
The following is an example of the conditional expression.
Example | Description |
(Tag_A != 1) && (Tab_B == 10) | If the value of Tag_A is not 1 and the value of Tag_B is 10, the result is 1. In other cases, it returns 0. |
Sin(Tag_A) == 1 | If the sine of Tag_A is 1, the result is 1. In other cases, it returns 0. |
Tag_A < 100 | If Tag_A is smaller than 100, the result is 1. In other cases, it returns 0. |
(Tag_A + Tag_B) < (Tag_A + Tag_C) | If the sum of Tag_A and Tag_B is smaller than the sum of Tag_A and Tag_C, then the result is 1. In other cases, it returns 0. |
(2) Command Expression
In Xpanel, multiple command expressions can be used. The command expression is a special script program. You can also use the functions in the script for command expression.
The priority of the command expression is different from scripts. If the operation condition of the command expression is satisfied, the command takes the highest priority. It indicates that the other object’s operations are not processed until the current command operation ends. Especially if the function called by the command expression has the same priority as the command.
For example, when you use the ‘RunScript’ keyword in the command expression, the called script will operate in parallel. The command does not wait until the script ends. Instead, the next command expression will be executed at the same time.
The following is an example of a command expression.
Example | Description |
Tag_A = 100; PageOpen(“NewPage”); | Sets the value of Tag_A to 100 and opens the page named “NewPage”. |
Tag_B = Tab_B + 1 | Increases the value of Tag_B by 1. |
Tag_A = 100; Tag_B = 1; RunScript MyLoop(); MakeCsv(“LogModel”,1); | Sets the value of Tag_A to 100 and Tag_B to 1, then executes the script named MyLoop(). Once the script is executed, the data logging model named “LogModel” will be saved in the SD memory as CSV. |