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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
(3)
Communications time
This section describes how to calculate approximate communications
time from the start of data transmission from the computer to the
completion of all communications after a reply is sent from the
AJ71
C24.
For TO to
T4,
see ( 1 ) and
(2)
on the previous page.
(a) To read data from the PC CPU to the computer
Communications time
=
T O
+
(longer time of T I
+
T2 or TW)
+
T3
+
T4
where,
TO.T3,T4
=
l l b a u d rate X the number of bits per character
(1
+
718
+
011
+
112 x the character length
f
T
T
4
L
Start bit
1
D a b length (7
0 .
8)
Paritv bit 10
or
11
=
maximum 1
scan
time (since data entry to the PC CPU is made
after END processing. If the PC CPU is not running, T I is 0.)
T2
=
value in Appendix
5
=
message wait time
(b)
To write data from the computer to the PC CPU
Communications time
=
T O
+
(longer time of T I
+
T2+ T3
+
T5 or-
+
T4
where,
I
TO, T4
=
l l b a u d rate
X
the number of bits per character
(1
+
718
+
011
+
l&x
the character length
5
T
T
L
Start bit
Data length (7 or 8)
Paritv bit 10
or
11
I
T I
=
maximum 1 scan time (since data entry to the PC CPU is made
I
after END processing. If the PC CPU is not running, T I is 0.)
I
T2.T3
=
value in ~ ~ ~ e n d i x
5~
I
(For functions processed i n 1 scan, T3 is 0.)
I
Tw
=
message wait time
I
=
1 scan time
(For functions processed i n one scan, T5 is 0.)
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