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Data Exchange with CPU Bus Units Section 8-6
Setup. If cyclic refreshing is not disabled and either of the following processes
is executed in an interrupt task, a non-fatal error will occur and the Interrupt
Task Error Flag (A40213) will turn ON.
• I/O refreshing is executed using IORF(097) or FIORF(225) (CJ1-H-R
CPU Units only) for the same Special I/O Unit.
• Data is read or written to or from the memory area using IORD (222) or
IOWR(223) for the same Special I/O Unit.
Whenever disabling a Special I/O Unit’s cyclic refreshing, be sure that the I/O
for that Unit is refreshed with IORF(097) or FIORF(225) (CJ1-H-R CPU Units
only) in the program at least every 11 seconds during operation. A CPU Unit
service monitoring error will occur in the Special I/O Unit if it is not refreshed
every 11 seconds.
8-6-2 CPU Bus Units
Data can be exchanged between CPU Bus Units and the CPU Unit through
the CPU Bus Unit Area, the DM Area, or FINS commands.
CPU Bus Unit Area (I/O Refreshing)
Data is exchanged each cycle during I/O refreshing of the CPU Bus Unit Area.
Basically, 25 words are allocated to each CPU Bus Unit based on its unit num-
ber setting. The number of words actually used by the CPU Bus Unit varies.
The Special I/O Unit Area ranges from CIO 1500 to CIO 1899 (25 words
× 16
Units).
Note With CJ1-H CPU Units, the CPU BUS I/O REFRESH instruction
(DLNK(226)) can be executed in the ladder program to refresh the
CIO Area words allocated to the CPU Bus Unit of a specified unit
number.
Transfer of Words Allocated in the DM Area
Each CPU Bus Unit is allocated 100 words in the DM Area in the range of
D30000 to D31599 (100 words
× 16 Units). There are three times that data
may be transferred through the words allocated to each Unit. The timing of
data transfers depends on the model being used.
1,2,3... 1. Data transferred when the PLC is turned ON.
2. Data transferred each cycle.
3. Data transferred when necessary.
Note With CJ1-H CPU Units, the CPU BUS I/O REFRESH instruction
(DLNK(226)) can be executed in the ladder program to refresh the
DM Area words allocated to the CPU Bus Unit of a specified unit
number.
CPU Unit
CPU Bus Unit
CPU Bus Unit Area
25 words/Unit
Trans-
ferred in
I/O
refresh-
ing
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