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• MEMORY_COMPARE

MEMORY_COMPARE

Type	Function
Description	Compares two different memory areas. The memory areas to be compared are specified at the inputs BUF1 and BUF2. A byte offset inside BUF1 and BUF2 can be set at the inputs BUF1_OFF and BUF2_OFF. These values determine at which byte offset the comparison of the memory areas is started. The number of bytes to be compared is specified at the CNT input.
Parameters	Inputs BUF1 Data type: ANY Description: Buffer to be compared with the buffer at BUF2. BUF1_OFF Data type: ANY_INT Description: Offset in bytes related to the beginning of the buffer BUF1. The value must be greater than or equal to zero. BUF2 Data type: ANY Description: Buffer to be compared with the buffer at BUF1. BUF2_OFF Data type: ANY_INT Description: Offset in bytes related to the beginning of the buffer BUF2. The value must be greater than or equal to zero. CNT Data type: ANY_INT Description: Number of bytes to be compared starting from the buffer offset. The value must be greater than or equal to zero. Output OUT Data type: INT Description: Result of the comparison. -1 BUF1 < BUF2 0 BUF1 = BUF2 1 BUF1 > BUF2 2 The length of BUF1 or the value of BUF1_OFF does not fit. The size of bytes to be compared assigned in CNT is larger than the size of BUF1 - BUF1_OFF. BUF1_OFF must be >= 0. Example BUF1 is of the type STRING with [Byte1Byte2Byte3Byte4]['123456'] where: Byte1 to Byte4 are the STRING header (the header requires 4 bytes). '123456' is the STRING content (6 bytes). With a CNT value >= 11 the output returns the value 2 (4 bytes + 6 bytes = 10 bytes). 3 The length of BUF2 or the value of BUF2_OFF does not fit. The size of bytes to be compared assigned in CNT is larger than the size of BUF2 - BUF2_OFF. BUF2_OFF must be >= 0. 12 Value of CNT not in range. 20 Internal error
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 OUT < -1 or OUT > 1 Error code
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. Further Info See the topic "General information on execution control with EN/ENO" for further details.
Example	Example in ST Data type declaration:    TYPE       Buffer1 : ARRAY[0..3] OF BYTE;    END_TYPE    TYPE       Buffer2 : ARRAY[0..3] OF BYTE;    END_TYPE 'Variables' table with declarations: Code in ST: Out := MEMORY_COMPARE(MyVar_Buf1, MyVar_Buf1Off, MyVar_Buf2, MyVar_Buf2Off, MyVar_CNT);