3.
SPECIFICATIO’NS .
I
_1
..
,,
MELSEC-A
3.6
Data Communlcrtlono Tr8nSmlSSiOn
Control
Function
This function uses the DC
codes
(DCl/DC3, DCUDC4) or DTR/DSR signals to
control data communications between the AJ71C24 and an external device.
The AJ71 C24 controls
its
data communications
by
using this function.
The following table shows the interfaces used and modes where transmis-
sion controls are enabled.
Tr8ns-
mkalon
Control
Functlon
Typo
of
Control
Inlortaco
Usod
I
DTWDSR
DSR control
-
controls
DTR control
Rs-232c
DClIDC3 transmission control
DC
code
DC1
/DC3
receive control
DC2/DC4 transmission control
DC2/DC4 receive control
Rs-232c
Rs-422
Modo.
Whoro
transmkslon
Controls
aro
Valid
Runarks
0
-
0
0
0
-
The
RS422
is
ignored.
DTWDSR
0
via both the
Controliod
Rs-232c
and -422.
OlOl
O
1
or DC
code
control
can
be
used.
-:
Disabled
0:
Enabled (Transmission is controlled)
3.5.1
Precwtbns
when
contrdllng
trrmkrlon
This section gives the precautions to take when using the AJ71C24 trans-
mission control function
(1) Deciding which items are required to control data communications
between the external device and the
PC
CPU
(a)
Is
the transmission control function used?
If
so,
which type
of
control is used?
(b)
How
is
transmission controlled?
(c)
If
DC code control is used, which combination
of
codes is utilized?
(DC1 to DC4 codes can be switched.)
(2) Conditions for using the transmission control function
(a) Transmission cannot be controlled using both DTR/DSR signals
and DC codes at the same time.
Select one type of control using the AJ71 C24 buffer’s transmission
control designation area (address 11AH). (See item (3) below)
(b)
Transmission is controlled via the RS-232 in the same way as via
the
RS-422.
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