Omron NX-SL3300 User Manual page 225

l Function Block Instance
When you place an instance of a function block definition in a program or another function block,
the function block definition is treated as a part of that program or function block.
Function block definitions that are called from a program or another function block are called
"instances".
Every instance of a function block has an identifier known as an instance name associated with it,
and every instance uses memory.
You can use a single function block definition to create more than one "instance". This allows you
to process different I/O data with the same function.
Instance name
Function block definition name
Instance name
Function block definition name
If you place instance names FB1_1 and FB1_2 for function block FB1 in the program, each in-
stance requires its own space in memory.
"Instances" cannot be read from other programs or function blocks. If an instance with the same
name as another instance is placed in a different program or another function block, that instance
will operate as a completely separate instance.
Precautions for Correct Use
In the following conditions, a user-defined function block will cause an error during the program
check when the program is built.
• The same function block instance was called more than once in the POU.
• The instance of the function block was registered as a global variable.
NX-series Safety Control Unit User's Manual (Z930)
Program POU
FB1_1
FB1
Variable
Memory area
declarations
reserved.
Algorithm
FB1_2
FB1
Variable
declarations
Memory area reserved.
Algorithm
6 Programming
Memory area
Memory for
instance
FB1_1
Memory for
instance
FB1_2
6
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