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1.
GENERAL DESCRIPTION
MELSEC-A
1.
GENERAL DESCRIPTION
This User's Manual describes the specifications, handling and transmission
control protocols of the AJ71C24-S6 computer link module.
The A J 7 1 C 2 4 3 6 has one RS-232C port and one RS-422 port. It is the
interface between a PC CPU and an external device (such as a computer or
printer) or t o the CPU of another PC station.
Dedicated transmission protocols 1 to 4 are used as transmission control
procedures on the A J 7 1 C 2 4 S 6 and a no-protocol mode and a bidirectional
mode are also available. The user can select and set these independently
for the RS-232C and RS-422 ports.
When using a dedicated transmission p r o t o c o l or t h e no-protocol
mode/bidirectional mode, data is transmitted using the codes as shown
below.
RS-232C o r RS-4Z cable
Computer
Automatic communications
after the
sequence
program
PC
END processing.
AJ71
CPU
,
C24
(ASCII code)
BIN code
Read
Transmined data
,
Write
Transmined data
\
\
- .
Transmitted data
,
0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0
,
-
(The AJ71 C24
converts
data between
-
(1 2 3 4 ~ )
BIN code and ASCII code.)
Fig. 1.1 Data Transmission with the Dedicated Protocol
I
IS-232C or RS-422 cable
Sequence
program
PC
TOIFFOM instructions
1 g p 1
External
(such
as
device
a computer, printer)
CPU
0 0 ~ to FFH
OOH to FFH
I
(Data is transmined in unchanged code through the buffer memory.)
I
Fig. 1.2. Data Transmission i n the No-Protocol Mode/Bidirectional Mode
Transmit
T
Receive
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