MEMCMP
The function MEMCMP allows the values of PLC variables in two different memory areas to be compared.
MEMCMP FUNCTION: DINT
Inputs
VAR_INPUT
pBuf1 : PVOID;
pBuf2 : PVOID;
n : UDINT;
END_VAR
Name | Type | Description |
|---|---|---|
pBuf1 | PVOID | Start address of the first memory area (the first data buffer). |
pBuf2 | PVOID | Start address of the second memory area (the second data buffer). |
n | UDINT | Number of bytes to be compared. |
The function compares the first n bytes in the two data buffers and returns a value that corresponds to their ratio.
Return parameter | Ratio of the first byte that is different in the first and second data buffers |
|---|---|
-1 | pBuf1 lower than pBuf2 |
0 | pBuf1 identical to pBuf2 |
1 | pBuf1 greater than pBuf2 |
0xFF | Incorrect parameter values. pBuff1 = 0 or pBuff2 = 0 or n = 0 |
Example of a call in FBD:
PROGRAM MAIN
VAR
Buffer1 : ARRAY[0..3] OF BYTE;
Buffer2 : ARRAY[0..3] OF BYTE;
CmpResult : DINT;
END_VAR
In this example, 4 bytes of data in Buffer2 are compared with those in Buffer1. The first differing byte is larger in Buffer1 than it is in Buffer2.
Requirements
|
Development environment |
Target system type |
PLC libraries to include (Category group) |
|---|---|---|
|
TwinCAT v3.1.0 |
PC or CX (x86, x64, ARM) |
Tc2_System (System) |