Omron CJ2 CPU - REV 10-2010 User Manual page 277

I/O Allocation Methods
Use one of the following two methods to allocate I/O.
• Automatic Allocation (Default)
When the Unit power supply is turned ON, I/O will be allocated according to the status of the con-
nected Units (e.g., the slot positions and unit numbers).
• Manual Allocation (I/O Table Creation)
You can create I/O tables using the CX-Programmer to specify the desired allocations. If I/O tables
are created, an error will occur if the I/O tables do not match the status of connected Units when the
CPU Unit Power Supply is turned ON.
The following table shows the differences between these two methods. Select the method according to
the purpose and needs of the system.
Allocation method
Item
Purpose
Creating I/O tables
Verifying the connected
Units against the I/O
tables
Operation used to allo-
cate I/O
CX-Programmer
Connected Units
required to create I/O
tables
Allocation method
Checking the I/O Allocation Method
You can use the I/O Allocation Status Word (A260) to check whether the I/O allocations have been
set manually or automatically.
Address
A260
CJ2 CPU Unit Software User's Manual
Automatic allocation
• Use this method when
checking for incorrect
Units is not required.
• Use this method when
user-set allocations are
not required (including
reserving unused
words).
Not required.
Unit not verified.
Allocated automatically.
Not required.
Required.
Automatic allocation (in order from the CPU Unit)
Name
I/O Allocation Status 0000 hex
BBBB hex
8 I/O Allocations and Unit Settings
Manual allocation
Creating I/O tables with
Units connected
Use this method to check
for incorrect Units.
Required.
Unit verified. (Operation cannot be started if the con-
nected Units do not agree with the I/O tables.)
Allocated manually.
Required
Required
Contents
Automatic I/O allocation
Manual allocation
Creating I/O tables with
user-set allocations
• Use this method to cre-
ate user-set allocations
(including reserving
unused words).
• Use this method to allo-
cate I/O without the
actual I/O Units (i.e.,
offline).
Not required.
Manual allocation (The
first address can be speci-
fied for each group.)
8-3
8