MEMCPY
The function MEMCPY can be used to copy the values of PLC variables from one memory area to another.
Notice | |
System crash or access to unauthorized memory areas Since the function directly accesses the physical memory, special care must be taken when using it. Incorrect parameter values can result in a system crash, or in access to forbidden memory areas. |
 | The behavior of MEMCPY is undefined if the destination and source memory areas overlap. This is the case, for example, when several values stored in an array are to be moved one position forward or backward. In such a case, use the function MEMMOVE. |
FUNCTION MEMCPY : UDINT
Inputs
VAR_INPUT
destAddr : PVOID;
srcAddr : PVOID;
n : UDINT;
END_VAR
Name | Type | Description |
|---|---|---|
destAddr | PVOID | Start address of the destination memory area. |
srcAddr | PVOID | Start address of the source memory area. |
n | UDINT | Number of bytes to be copied. |
The function copies n bytes from the memory area with the start address srcAddr to the memory area with the start address destAddr.
Return parameter | Meaning |
|---|---|
0 | Incorrect parameter values. destAddr == 0 or srcAddr == 0 or n == 0 |
> 0 | If successful, the number of bytes copied (n). |
Example of a call in FBD:
PROGRAM MAIN
VAR
Buffer1 : ARRAY[0..3] OF BYTE;
Buffer2 : ARRAY[0..3] OF BYTE;
CpyResult : UDINT;
END_VAR
In the example, 4 bytes are copied from Buffer2 to Buffer1.
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) |