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10. COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
( c o n t i n u e d )
Name
3idirectional mode designa-
:ion
area
Time-out check time designa-
tion
area
Data validlinvalid designation
area
at simultaneous lransmis-
Bidirectional mode check sum
enableldisable designation
area
Error storage area for data
send
Error storage area for data
received
Description
Wnetner thc ~ n t c r f a c c commLnws1
ons
modc is no-proloco
or
old
rec-
t onal
i s
dcslgnated w 1h
a
TO mslrdcuon in a s e q w n c c program
0: No-protocol mode (default)
1 : Bidirectional mode
r
The time-out check time (until the reception of
a
response
after
trans-
mission of data t o the computer) is designated with
a
TO instruction in
a sequence program.
OH
:Time-out is not checked (default)
1 H to FFFFH : Time-out check lime (100 msec units)
The most significant bit in the area is not regarded
as
the sign bit. The set value is regarded t o designate
value i n the
range
of
1
through
65535.
How the receive and send data at
an
AJ71C24 is processed i f data
transmission at
a
computer and
an
AJ71C24 occurs simultaneously is
designated with a TO instruction
on
a sequence program.
(Section 10.6 covers silmultaneous transmission)
I
I
---
I
.
Receive data (OOH: valid. 01
H:
Invalid)
.
Send data (OOH: valid, 01
H:
Invalid)
b15
to
b8 b7
to
M
Whether
or
not check sum is appended for bidirectional mode com-
munications is designated with a TO instruction i n
a
sequence pro-
gram.
(This designation is not related t o the setting of DIP switch SW21.)
1 1 4 ~ 1
0 : Check sum enabled (default)
1 : Check sum disabled
(default: 000H)
0
If
an
error occurs during data communications, the error code is
transmitted by
an
AJ71C24.
(The
area
designated i n 117H retains the
error
code of the last data
receive
error.)
OH
: Normal termination (no error)
0001 H
10
]
: Abnormal termination (error)
0082H
Section 11 2 gives error code details.
The area described above is the special
a p p l i c a t i o n s
area
f o r b i d i r e c t i o n a l
mode communications.
I
For
o t h e r
special applications areas used
f o r
data communications, see
S e c t i o n
3.5,
section
5,
and section 7.
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