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• BUF_TO_*

BUF_TO_*

Type	Function block
Description	Allows to copy elementary data types from a byte stream to a variable, an array or elements of a user-defined structure. Little-/Big-Endian format is possible for the byte stream. Therefore an automatic data format conversion is supported. This function block is useful for the data transfer or the communication among applications which are executed on different hardware platforms (Little-/Big-Endian). Operation After a rising edge has been put to the REQ input, the copy process starts. As defined in the BUF_FORMAT parameter, the data are converted into Little-/Big-Endian format (see the note below). The size of the destination DST is checked before copying. After the copy process has finished correctly, DONE is set to TRUE. In case of any occurred errors, ERROR is set to TRUE and STATUS gets a value unequal to zero which represents the current error message. These values are kept until a falling edge is put to the REQ input. A new rising edge at REQ starts a new copy process. Timing diagram
Notes	' * ' is a placeholder for the supported data types. The FB is available for the data types BYTE, WORD, DWORD, LWORD, SINT, INT, DINT, LINT, UDINT, UINT, ULINT, USINT, TIME, REAL, LREAL, STRING, WSTRING, LTIME, LDATE, LTOD, and LDT. For the STRING/WSTRING data type the operation is different to the following described. For information about the handling of the BUF_TO_STRING/BUF_TO_WSTRING function block click here. It is not allowed to use the same addresses for the source and the destination! The BUF_FORMAT parameter is not evaluated and has no effect for some data types such as BYTE or SINT. Function blocks have to be instantiated. The instance name of the function block has to be declared in the 'Variables' table of the POU where the FB is going to be used. The instance name must be unique within the POU.
Parameters	Inputs REQ Data type: BOOL Description: A rising edge starts the copy operation. BUF_FORMAT Data type: BOOL Description: TRUE indicates that the buffer data are in Big-Endian format, whereas FALSE indicates Little-Endian format. The parameter is not evaluated and has no effect for some data types such as BYTE or SINT. BUF_OFFS Data type: ANY_INT Description: Byte address in the buffer. The value must be greater than or equal to zero. BUF_CNT Data type: ANY_INT Description: Number of bytes to be copied. The value must be greater than or equal to zero. Input/Output BUFFER Data type: ANY Description: Source array (byte stream). DST Data type: * or ARRAY_OF_* Description: Destination array or variable of standard data type *. Outputs DONE Data type: BOOL Description: TRUE indicates that the data are copied successfully. ERROR Data type: BOOL Description: TRUE indicates an occurred error. STATUS Data type: INT Description: Indicates the status of the copy process. For a detailed description of the possible status click here.
Additional information	Possible status of the copy process Special behavior of BUF_TO_STRING/BUF_TO_WSTRING BUF_TO_BYTE example