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Type
| Function |
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Description
| The overloaded function TO_USINT converts an input value of various data types into an output value of the data type USINT (see description of the input for the supported data types). |
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Parameters
| Input
 IN
| Data type: | The function is available for the following input data types:
- BOOL, BYTE, WORD, DWORD, LWORD
- Integers: SINT, INT, DINT, LINT, UINT, UDINT, ULINT
- Floating point numbers: REAL, LREAL
- STRING, WSTRING
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Output
OUT
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Conversion rules
| ANY_BIT conversion
The conversion is done by copying the input value bitwise to the output value, i.e., a binary transfer from the input data type to the output data type is performed.
If the input data type is bigger than the USINT output (> 8 bits), only the bits 0 to 7 of the input value are copied to the output value.
ANY_INT conversion
The data type conversion is done as follows:
- The source data type is converted to the largest data type of the same generic data type group (for example, an USINT value is converted to an ULINT value or a SINT value to a LINT value). The source value remains unchanged.
- The result is converted to the largest data type of the generic data type group to which the target data type belongs to (for example, a LINT value is converted to a ULINT value in case of an ANY_UNSIGNED conversion).
- The result is converted to the target data type.
Input size <= output size: If the input data type is smaller or has the same size than the target data type, all bits of the value are copied to the output. In case of an unsigned integer input value, the "unused" bits in the target data type are set to 0. In case of a signed integer input value, the most significant bit is no longer considered as sign bit.
Input size > output size: If the input data type is bigger than the target data type, only the bits of the input value that fits into the target data type are copied to the output value (for example, for a TO_UDINT conversion only the bits 0 to 31 of the input value are copied and for a TO_USINT conversion only the bits 0 to 7 are stored into the output variable.)
Example:
out := TO_USINT(INT#-5);
- The INT value INT#-5 is converted to the LINT value LINT#-5.
- The LINT value LINT#-5 is converted to the ULINT value ULINT#18446744073709551611.
- The ULINT value ULINT#18446744073709551611 is converted to the USINT value USINT#251.
ANY_REAL conversion
The type conversion is divided into two steps. First the floating point value is rounded to the next higher absolute integer according to standard rounding rules (for example, 2.5 is rounded to 3 and -2.5 is rounded to -3). In the second step the rounded input value is converted to the least significant bits of the output value.
Note
Due to the loss of significance in REAL values, only REAL values less than LINT_MAX should be applied. |
ANY_STRING conversion
- The string value has to be a valid numeric literal of the output data type, otherwise the function returns the value 0 and the runtime error 'Format string failure' occurs (see the note below).
- Additional characters except than whitespaces after or before the numeric literal are not permitted. The function returns the value 0 and generates a 'Format String Failure' if the string value contains unallowed characters.
- All leading and trailing whitespaces in the input string are ignored.ASCII codes regarded as whitespaces:
| Character | Value |
| Horizontal tab | 9 (09h) |
| Line feed | 10 (0Ah) |
| Vertical tab | 11 (0Bh) |
| Form feed | 12 (0Ch) |
| Carriage return | 13 (0Dh) |
| Blank | 32 (20h) |
- If the input value is out of the range for the output data type, the overflow value is returned and the runtime error 'Format string failure' occurs (see the note below).
- Binary, octal, hexadecimal and decimal integers are allowed. For example:INT#2#0101 (binary representation of 5)INT#8#606 (octal representation of 390)INT#10#100 (decimal representation of 100)INT#16#00FA (hexadecimal representation of 250)
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. |
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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
RFC/NFC/AXC F 3152 | Output value
AXC F 2152 |
| Overflow value | Overflow value | Overflow value |
| Real value >= LINT_MAX | 0 | 0
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| Real value <= LINT_MIN | 0 | 0 |
| Real value > ULINT_MAX | 0 | LIMIT (maximum value) |
| Real value < -ULINT_MAX | 0 | 1 |
| Real: NaN | 0 | 0 |
| Real: inf+ | 0 | LIMIT (maximum value) |
| Real: Inf- | 0 | 1 |
| Non-literal string (integer
num, literal binary, octet, hex, dec) | 0 | 0 |
| String overflow (integer num,
literal octet, hex, dec) | Overflow value | Overflow value |
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Examples
| Examples in ST
out := TO_USINT(16#7F); (* results in 127 *)
out := TO_USINT(16#FFFF); (* results in 255 *)
out := TO_USINT(16#AFFFFFF0); (* results in 240 *)
out := TO_USINT(INT#127); (* results in 127 *)
out := TO_USINT(INT#32767); (* results in 255 *)
out := TO_USINT(INT#-32768); (* results in 0 *)
out := TO_USINT(SINT#-128); (* results in 128 *)
out := TO_USINT(REAL#2.55E+002); (* results in 255 *)
out := TO_USINT(REAL#2.56E+002); (* results in 0 *)
out := TO_USINT('123'); (* results in 123 *)
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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.
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