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2. SYSTEM CONFIGURATIONS
MELSEC-A
2.3
System Configurations and Available Functions
The AJ71C24 is a link module to connect an external device (such as a
computer) and a PC CPU. The system can consist of a single external device
and from 1 to 32 PC CPU stations (1 : 1 to 32 ratio system) or two external
devices and from 1 to 32 PC CPU stations (2
:
1 to 32 ratio system). The
connection may be made in two ways: using the RS-232C port or the RS-422
port.
2.3.1
1
:
1
ratio of an external device (computer) to a PC CPU
(1) The system configuration for a 1 : 1 ratio of an external device (such as
a computer) to a PC CPU is shown in Fig. 2.2 below.
(Mode: [ ]
-
[
I)
in the figure indicates the range of setting set with the
mode setting switch of an AJ71C24 (see Section 4.3.1).
External
device
1
(such as a computer.
printer. CRT)
RS-232C or RS-422 interface
I
\
RS232C or RS.42'2 interface
ezsion
base
(1) Use of the RS-232C and the RS-422 interfaces differs in that the
RS-422 is used to connect long distances (up to 500 m (1640.5 ft))
and the RS-232C is used to connect short distances (a maximum of
15 m (49.2 ft)).
(2) To have the RS-232C communicate over a distance greater than 15
m (49.2 ft), use a modem or RS-232ClRS-422 converter between the
external device and the AJ71C24.
Fig. 2.2 System Configurations (I)
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