17
Functions Section 1-2
Abnormal I/O Unit Addresses and Registered I/O Unit Addresses
1-2-5 I/O Configuration Changes
The I/O Unit interface automatically recognizes the I/O Unit configuration each
time the Communications Unit is started up, and stores this as the normal
configuration.
Note 1. If the I/O Unit configuration is changed while the Communications Unit is
turned ON, a configuration error will occur. Do not change the I/O Unit con-
figuration while power is being supplied to the Communications Unit.
2. If a configuration error occurs on the I/O Unit interface, I/O refreshing of all
I/O Units will stop. Even if a configuration error occurs, communications
with the DeviceNet Network will continue, using the initial I/O Unit configu-
ration. An error processing program section must therefore be included in
the CPU Unit to regularly check whether or not a configuration error has
occurred (status bit 1) and to process abnormal I/O Unit addresses.
If the I/O Unit configuration is changed, perform the following operations,
according to the DeviceNet area allocation method. For details about I/O allo-
cation, refer to DeviceNet Operation Manual (W267).
Default Allocations Because the allocation size of the Communications Unit changes together
with changes to the I/O Unit configuration, a verification error will occur on
DeviceNet if the scan list is enabled, as follows:
• Master Unit 7-segment display will show d6, Slave I/O size mismatch.
• Master status bits 14 and 7 will turn ON.
Perform the following operations, according to the status of the input/output
areas.
Allocation Areas Do Not Overlap with Other Slaves
Remote I/O communications will be performed unchanged with the new con-
figuration. Check the Verification Error Bit and, if required, perform processing
to disable the allocated words in the CPU Unit. Also check the number of
points for the changed I/O Unit and its allocation area on the I/O Unit inter-
face, and re-register the scan list (first set the Scan List Enable software
switch to OFF, and then set it to ON after checking the I/O size).
Allocation Areas Overlap with Other Slaves
In this case, I/O area duplication will also occur on the DeviceNet, as follows:
• Master Unit 7-segment display will show d0, I/O area duplication.
• Master status bits 14 and 4 will turn ON.
Check the Verification Error Bit, and perform processing to disable the allo-
cated words in the CPU Unit. Also change the Slave node number so that the
allocation area does not overlap with any other, and re-register the scan list
(first set the Scan List Enable software switch to OFF, and then set it to ON
after checking the I/O size).
Note If the scan list is disabled, there will be no changes made in the DeviceNet
Master Unit, even if the Communications Unit input/output sizes change. Be
sure to use the Scan List Enable Mode for normal operations.
The bits corresponding
to I/O Unit with errors
are turned ON. Bits 8 to
15 correspond to
addresses 0 to 7.
1: Error
0: No error, or not
part of network
The bits corresponding
to registered I/O Units
are turned ON. Bits 0 to
7 correspond to
addresses 0 to 7.
1: Registered
0: Not registered
Bit
+1 wd
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