10
Function Blocks Section 1-2
Number of Instances Multiple instances can be created from a single function block definition. Up to
either 256 or 2,048 instances can be created for a single CPU Unit depending
on the CPU Unit model. The allowed number of instances is not related to the
number of function block definitions and the number of tasks in which the
instances are inserted.
Parameters Each time an instance is created, set the real I/O memory addresses or con-
stants for I/O variables used to pass input data values to instances and obtain
output data values from instances. These addresses and constants are called
parameters.
Here, it is not the input source address itself, but the contents at the input
address in the form and size specified by the variable data type that is passed
to the function block. In a similar fashion, it is not the output destination
address itself, but the contents for the output address in the form and size
specified by the variable data type that is passed from the function block.
TIMER_FB
TIMER_FB
TIMER_FB
instance_A
instance_A
instance_B
Function Block Definition
TIMER_FB
Variable Definitions
Internal variable: WORK_NUM
Use same internal variables.
Use different internal variables.
ab
c
Input 0.00
Instance of Function Block Definition A
Input 3.00
Output 2.00
Set the constants or
input source addresses
from which to pass data.
Set the constant or
output destination
address to which to pass
data.
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