Mitsubishi Electric AJ71C24-S6 User Manual page 100

6. DATA COMMUNICATIONS USING AN M : N MULTIDROP LINK
MELSEC-A
(1) A slave station that requires data communications with a PC CPU
transmits a communications request to obtain the access right to the
master station.
An example of the message format is shown in (2) below.
(
(2) The master station transmits an approval response to the slave station
that made the communications request.
(An example of data communications using dedicated protocol
1)
- 1
"1 The command symbol
--..
...,.-
.--
'M'
in this example is
.
I I
indicated only for ex-
Master station
computer (SOH)
I
?
I F!?K I 2 . I
~ n a b l e /
I
transfer c&nmand to
leonl ( 8 2 ~ 1
m
Section 8.3 tells how to
OSH 38H13CH38n13Ln 5S1
read the message
[2] message format figure.
+ :
Computer with the access right
Masterstah
+
(Before (6)) +(After (6))
(3) After performing data communications with a PC CPU within the maxi-
mum data communications time set among computers, the slave station
that received an approval response executes the processing as shown
in
(5)
below.
(4)
The master station that transmitted the approval response and the slave
stations that do not have the access right check the access right time
of the slave station that obtains the access right, and, ignore received
data which is addressed to other stations.
If the access right time of a computer with the access right exceeds the
maximum data communications time, each computer executes the
processing mentioned in (7).