8.
COMMUNICATIONS USING
DEDICATED
PROTOCOLS
MELSEC-A
8.2
Programming Hints
8.2.1
To
wtte
data
to
the
apeckl
uw
area
In
bunw
memory
Buffer memory is not backed up by a battery.
When the power is turned ON, the PC CPU is reset, or
the
mode is
switched. all data
in
the
buffer
is set to default values. Therefore,
whenever the power
is
turned ON, the CPU is reset, or
the
mode is
switched, any data which has been changed from a default value must
be written to the buffer.
Except for the mode-switching area, data can only be written to the
special applications area using the TO instruction
in
a sequence pro-
gram.
If
data is written to the buffer memory using the command
in
a
computer program, the AJ71C24 will not operate correctly. Never try
to write data using a computer program.
If
the following functions are used in combination with the dedicated
protocol, make sure to allocate the user area
in
buffer memory
so
that
the same area will not be used by different functions.
If the same area is allocated to different functions, the data
in
this area
is rewritten and communications will not be correctly executed.
0
No-protocol mode transmission or bidirectional mode transmis-
0
No-protocol mode receive
or
bidirectional mode receive
0
Buffer memory read/write (CR/CW command) function
0
On-demand function
sion
The memory areas preceding and following the special use area cannot
be allocated as a single area. The areas
OH
to
FFH
and
120H
to
7FFH
must be recognized as independent areas.
Example:
I
FFH
I
OOH
11FH
120H
I
The
on-demand buffer area cannot
be allocated in
this
manner
If the designation is made to process the send/receive data
in
the
no-protocol mode
or
bidirectional mode
in
units
of
words or bytes, the
on-demand data is processed
in
the same designated unit.
8-2
c
i.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
