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3-2
Section
Functions
32
Even if an error occurs in the I/O Unit interface after initialization is completed,
PROFIBUS-DP communications will continue normally. Therefore, an error
processing program section must be included in the CPU Unit to check the
status of the Communication Unit for errors that have occurred and to identify the
error type and location.
3-2-3 Allocating I/O
This section explains how words for a MULTIPLE I/O TERMINAL are allocated
in the output area and input area of the Master. For details of remote I/O
functions in the output area and input area of the Master such as word
specification, fixed allocation, and user-set allocation, refer to the
PROFIBUS-DP Master Unit Operation Manual (W349)
.
Output Area
The output area contains output bits in the same order as the I/O Units are
connected on the I/O Unit interface.
Input Area
The input area contains the Communication Unit status (two words), and input
bits in the same order as the I/O Units are connected on the I/O Unit interface.
Area corresponding to
Communication Unit
Output bits on
the I/O Unit
interface
I/O Unit interface
status
Input bits on the I/O
Unit interface
Output area
Input area
The input and output bits for the I/O Unit interface are allocated in the
PROFIBUS-DP input and output areas in 16-point (one word) increments.
Error Processing