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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 com-
pletion of all communications after a reply is sent from the AlSJ71C24.
For TO to T4, see (1) and (2) on the previous page.
(a) To read data from the AlSCPU to the computer
Communications time
=
TO
+
(longer time of T i
+
T2 or TW)
+
T3
+
T4
where,
I
TO, T3, T4
=
tlbaud rate X the number of bits per character
(1
+
718
+
011
+
1 1 2 1 ~ the character length
A
.
A
A
-
Stop bit (1 or 2)
Parity bit (0 or 1)
Data lenath 17 or 8)
I
Start b i t -
'
T I
=
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
TW
=
message wait time
(b)
To write data from the computer to the AlSCPU
Communications time
=
TO
+
(longer time of T I
+
T2+ T3
+
T5 or
TW)
+
T4
where,
TO, T4
=
llbaud rate
X
the number of bits per character
(1
+
718
+
011
+
m
x the character length
-
Stop bit (1 or
2)
1
Parity bit (0 or I )
Data length (7 or 8)
Start bit
T I
= maximum 1 scan time (since data entry to the PC CPU is made
after END processing. If the PC CPU 1 s not running. T I is 0.)
T2, T3
=
value in Appendix 5
(For functions processed in
1
scan, T3 is 0 . )
TW
=
message wait time
T5
= 1 scan time
(For functions processed in one scan, T5 is 0.)
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