7 Serial Communications
7 - 6
NX-series Communications Interface Units User’s Manual (W540)
7-3 Data Used by the Serial Communica-
tions Protocol
If the system configuration does not allow you to use serial communications instructions for CIF Units,
you must program processing for the serial communications protocol in the user program. This section
describes the data that is used in processing of the serial communications protocol between the CPU
Unit or communications master and a CIF Unit.
Precautions for Correct Use
Refer to 1-4-2 Conditions for Using Serial Communications Instructions for CIF Units on page
1-8 for detailed conditions on using the serial co
mmunications instructions for CIF Units.
The data that is sent from a CIF Unit to the CPU Unit or communications master is called the input noti-
fication data. The data that is sent from the CPU Unit
or communications master to the CIF Unit is
called the output notification data.
All of the input notification data and ou
tput notification data can be set in the I/O allocations on the Sup-
port Software. Refer to Section 5 I/O Data Specifications for details on the data that yo
u can set in the
I/O allocations.
The following table gives the data indices for I/O allocation of
the input notification and output notifica-
tion data.
In each I/O refresh cycle, the CPU Unit or communications ma
ster and the CIF Unit exchange input
notification data and output notification data.
7-3-1 Input Notification Data and Output Notification Data
Data Index (hex)
Input Notification Data 6000 and 6001
Output Notification Data 7000 and 7001
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