Mitsubishi Electric Melsec A Series - Page 12

1. INTRODUCTION
--------------------
MELSEC·A
1.1.2
Data communication between the A2CCPU and the remote terminal module
(1) Maximum
number
of remote terminal modules to be connected
A maximum of 14 remote terminal modules (a maximum of 7 AJ35PTF-
R2 RS-232C modules) can be connected to
the
A2C. (See Section 2.2.)
(2) Data communication with remote terminal modules
(a) Perform the following initial setting.
1)
The first station
number
of
the
remote terminal module
2) Protocol
See Section 4.2.9
for
details of initial setting.
(b) Execute data communication with the FROM/TO instruction.
See the ACPU Programming Manual (Common Instructions)
for
4
details of the FROM/TO instruction.
(b) Transmission of
designated
data
by
I
executing TO instruction
A2C
Station:
1
(a) Sequence
program
execution
I
-:
CPU
I/O
HXf
0
I
TopIH91KOIooIK11-
Remote
PRCIM1IYOI-
MINI-S3Iink
Station:
9
terminal
,
module
,
cOmPI~ignal
!=:i?
,
n
..!.-
Y21
@[]
I/O
1------
I/O
(c)
Tra~mission
Station:
n
Station:
5
of
complete
signal
Data
communication
with the remote terminal
module
is executed as
described
below.
(a) The FROMITO and PRC
instructions
are executed by the sequence program.
(b) The request to
send
designated
data
or the data is transmitted
by
executing
the FROMITO instruction.
1)
At FROM
instruction
execution
: Data
send
request
2)
TO
instruction
: Data
sending
(c) The remote terminal
module
sends the
completion
signal
of
data
send or receive to
the
A2C.
Cd)
The A2C turns ON
the
complete
signal
when it received the send/receive
complete
signal
from
the
remote
terminal
module.
•
Fig.
1.2
Data
Communication
between
the
A2C
and
the
Remote
TermInal
Module
(3) Response time
Communication of
8
data with one FROM/TO instruction requires
ap-
...
proximately 400 msec (when scan time is 100 msec). •
1-4