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3-2
Section
Functions
35
Abnormal I/O Unit Addresses and Registered I/O Unit Addresses
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
Note
The high and low bytes in this status word are swapped when the transfer mode
is set to Little Endian (see section 2-2-2).
3-2-5 I/O Configuration Changes
The I/O Unit interface automatically recognizes the I/O Unit configuration each
time the Communication Unit is started up.
Note
1. If the I/O Unit configuration is changed while the Communication Unit is
turned ON, a configuration error will occur. Do not change the I/O Unit
configuration while power is being supplied to the Communication 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 PROFIBUS-DP Network will continue, using the initial I/O Unit
configuration. 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 configuration is changed, then the PROFIBUS-DP System should be
reconfigured, see 2-3-2.