Omron CX-PROGRAMMER 5.0-FUNCTION BLOCK OPERATION Operation Manual page 56

Restrictions on Function Blocks
No Function Block
Connections
Downloading in Task Units
Programming
Console Displays
Online Editing
Restrictions
Error-related
Restrictions
Prohibiting Access to
FB Instance Areas
A function block's input cannot be connected to another function block's out-
put. In this case, a variable must be registered to transfer the execution status
from the first function block's output to the second function blocks input.
0.0
FB1
FB2
EN
XIN1
XOUT
D100
XIN2
Tasks including function blocks cannot be downloaded in task units, but
uploading is possible.
When a user program created with the CX-Programmer is downloaded to the
CPU Unit and read by a Programming Console, the instances will all be dis-
played as question marks. (The instance names will not be displayed.)
The following online editing operations cannot be performed on the user pro-
gram in the CPU Unit.
• Changing or deleting function block definitions (variable table or algo-
rithm)
• Inserting instances or changing instance names
Note The instance's I/O parameters can be changed, instances can be
deleted, and instructions outside of an instance can be changed.
If a fatal error occurs in the CPU Unit while a function block definition is being
executed, ladder program execution will stop at the point where the error
occurred.
Program
Instance name
0.0
FB
EN ENO
D100 D200
AAA BBB
In this case, the MOV AAA BBB instruction will not be executed and output
variable D200 will retain the same value that it had before the function block
was executed.
To use a function block, the system requires memory areas to store the
instance's internal variables and I/O variables.
Function block instance
area
Non-retained
Retained
Timer
Counter
If there is an instruction in the user program that accesses an address in an
FB instance area, the CX-Programmer will output an error in the following
cases.
0.0
FB1
EN
D3000
XOUT
0.0
FB2
EN
D3000
XIN1
D100
XIN2
FB definition
Body
LD P_On
10.0
++ AAA
Fatal error occurs here.
MOV AAA BBB
Initial value of Initial value
start address of size
H512 896
H1408 128
T3072 1,024
C3072 1,024
Section 2-3
Temporary variables
transfer the value from
FB1 to FB2.
Allowed data areas
CIO, WR, HR, DM, EM
HR, DM, EM
TIM
CNT
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