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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
8.1
Data Flow i n Communications with Dedicated Protocols
8.2
Programming Hints
8.2.1
To write data to the special applications area in buffer memory
8.2.2
PC CPU operation during data communications
The descriptions are as given in the respective corresponding sections in
the AJ71C24-S8 User's Manual.
8.2.3
Precautions during data communications
Except for the following, the precautions are all given in the corresponding
section in the AJ71C2448 User's Manual.
(Precautions (2) and (4) in the manual are changed as follows.)
(2) Framing errors in the computer
A framing error might occur in the computer if nothing is sent from the
AJ71 UC24 to the computer via the RS-422 interface.
In this case, set the computer to ignore all data sent from the AJ71 UC24
until an ENQ, ACK or NAK code is transmitted.
(4) Data link error processing
The AJ71UC24 enters the standby state (see Section 3.6 110 Signals
List for CPU) if a data link or network error occurs during communica-
tions with a PC CPU (of a number other than FFH) of another station
on MELSECNET (11) or MELSECNETIB.
If such an error is detected by the computer when executing a time
check, send a clear command (EOT or CL code, see Section 8.4.5 (1))
to initialize the transmission sequence.
8.3
Basics of Dedicated Protocol Control Procedures
8.4
Basic Formats of Dedicated Protocol
8.4.1
Control format
1
8.4.2
Control format 2
8.4.3
Control format 3
8.4.4
Control format 4
The descriptions are as given in the respective corresponding sections in
the AJ71C24-S8 User's Manual.
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