|
Type
| Function |
|
Description
| Extracts the leftmost characters of a string applied to IN. L specifies the number of characters to be extracted from IN. |
| Notes |
- When the string output is longer than 80 characters and the FU is directly connected to another FU, temporary string variables of size 80 are used. Calculation/usage will fail. If the result of the operation is longer than 80 characters, then a 'String too short' message will be logged and the output is set to an empty string or the last valid value is kept, respectively. Use an intermediate local variable in-between.
- Problem for calculation of position and length: Characters in WSTRING can have a size of 2 bytes or 4 bytes. Due to this, there may be calculation problems on 4-byte containing character STRINGs with 2-byte oriented position and length.
|
|
Parameters
| Inputs
 IN
| Data type: | WSTRING |
| Description: | Input string. |
L
| Data type: | ANY_INT |
| Description: | Number of characters to be extracted. |
Output
OUT
| Data type: | WSTRING |
| Description: | Output string. |
|
|
Error behavior
| Error behavior
The following table shows the errors which may occur while executing the function and the value returned by the function in the corresponding error case.
| Error case | Output value |
| L < 0 | Empty string '' |
| L > len(IN)(len(...) = actual string length) | Empty string '' |
| Resulted string too short | Empty string '' |
If any of the listed errors occurs, a string error is written to the Online log in the MESSAGES window.
Note
Controller stop on string error: The controller can be automatically stopped when a string error occurs. This allows you to locate the error in your project. To enable the automatic stop of the controller in case of a string error, activate the  button in the Cockpit toolbar of the controller. |
|
|
Additional information
| EN/ENO behavior
The POU is only executed if TRUE is applied to the EN input. If EN = FALSE, the POU is not executed and ENO = FALSE indicates the inactivity.
If any of the errors listed under "Error behavior" occurs while executing the function, ENO is set to FALSE.
|