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Data Exchange with CPU Bus Units Section 8-6
FINS Commands The CMND(490) instruction can be added to the ladder program to issue a
FINS command to the Special I/O Unit.
FINS commands can be transmitted to Special I/O Units in other PLCs in the
network, not just the local PLC.
Special I/O Unit Initialization
Special I/O Units are initialized when the PLC’s power is turned on or the
Unit’s Restart Bit is turned ON. The Unit’s Special I/O Unit Initialization Flag
(A33000 to A33515) will be ON while the Unit is initializing.
I/O refreshing (cyclic I/O refreshing or refreshing by IORF(097) or FIORF(225)
(CJ1-H-R CPU Units only) will not be performed for a Special I/O Unit while its
Initialization Flag is ON.
Disabling Special I/O Unit Cyclic Refreshing
Ten words are allocated to each Special I/O Unit in the Special I/O Unit Area
(CIO 2000 to CIO 2959) based on the unit number set on the front of each
Unit. The data in the Special I/O Unit Area is refreshed in the CPU Unit every
cycle during I/O refreshing (just after execution of the END(001) instruction).
I/O refreshing may take too long if too many Special I/O Units are installed. If
I/O refreshing is taking too much time, the PLC Setup can be set to disable
cyclic refreshing for particular Special I/O Units. (The Special I/O Unit Cyclic
Refreshing Disable Bits are in PLC Setup addresses 226 to 231.)
If the I/O refreshing time is too short, the Unit’s internal processing will not be
able to keep pace, the Special I/O Unit Error Flag (A40206) will be turned ON,
and the Special I/O Unit may not operate properly. In this case, the cycle time
can be extended by setting a minimum cycle time in the PLC Setup or cyclic
I/O refreshing with the Special I/O Unit can be disabled.
Then cyclic refreshing has been disabled, the Special I/O Unit’s data can be
refreshed during program execution with IORF(097) or FIORF(225) (CJ1-H-R
CPU Units only).
Note IORF(097), FIORF(225) (CJ1-H-R CPU Units only), IORD (222), and
IOWR(223) can be executed for Special I/O Units from interrupt tasks. When
doing so, always disable the Special I/O Unit’s cyclic refreshing in the PLC
CPU Unit
Special I/O Unit
FINS
com-
mand
transmis-
sion
The FINS command is trans-
mitted when CMND(490) has
been executed in the program.
CPU Unit
Special I/O Unit
CPU Unit
Serial Communications
Unit
Serial Communications
Unit
The FINS command is
transmitted when
CMND(490) has been
executed in the program.
FINS command transmission
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