8-25
8 I/O Allocations and Unit Settings
CJ2 CPU Unit Software User’s Manual
8-2 Setting CPU Bus Units and Special I/O Units
8
8-2-2 Data Exchange
z FINS Commands
The CMND(490) instruction can be added to the ladder program to send a FINS command to the
Special I/O Unit.
Note FINS commands can be transmitted to Special I/O Units in other PLCs in the network, not just the local PLC.
z 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
(A502.00 to A507.15) is turned ON. The Unit's Special I/O Unit Initialization Flag (A330.00 to
A335.15) will be ON while the Unit is initializing.
I/O refreshing (cyclic I/O refreshing or refreshing by IORF(097) or FIORF(225) will not be performed
for a Special I/O Unit while its Initialization Flag is ON.
z 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 (A402.06) 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 pro-
gram execution with IORF(097) or FIORF(225).
Special I/O Unit
CPU Unit
CMND
The FINS command is trans-
mitted when CMND(490) has
been executed in the program.
FINS
command
transmis-
sion
Special I/O Unit
CPU Unit
CPU Unit
CMND
Serial Communications Unit
Serial Communications Unit
FINS command transmission
The FINS
command is
transmitted when
CMND(490) has
been executed in
the program.
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