Table of Contents
Advertisement
3.
SPECIFICATIONS
MELSEC-A
3.3.2 Functions available in the no-protocol mode
(I)
Functions in the no-protocol mode
Send (PC
CPU
-+
ex-
ternal
device)
Receive
(External
device
-
PC CPU)
A PC CPU uses the TO instruction to
output data written to an AJ71C24
buffer memory area i n unchanged
code to an external device.
A PC CPU uses the FROM instruction
to read from an AJ71C24 buffer
memory which was transmitted from
an external device.
I
PC CPU State
I
Number of Poin
Processed
per
Communications
I
I
O N
I
OFF
I
(2)
Receive completion by the completed code and by the completion data
length
127 words
(default value).
Can be
changed with
buffer size set-
ting (see Sec-
tions 6.4.4 and
6.4.5.).
There are two waysto complete the data receive when an AJ71C24 is
receiving data from an external device:
(a) Reading the received data using the receive completed code
(receive of variable-length data)
0
When an AJ71C24 receives the receive completed code which is
set in the buffer memory by the user from an external device, the
AJ71C24 transmits a received data read request t o the sequence
program.
The sequence program, in response t o the read request, reads the
received data up to the receive completed code transmitted by the
external device.
0
The user can freely set the receive completed code.
(b) Reading the received data using the receive-completion data length
(receive of fixed-length data)
o
When an AJ71C24 receives data of a designated length which is set
in the buffer memory by the user from an external device, the
AJ71C24 transmits a received data read request t o the sequence
program.
Section 9
The sequence program, in response t o the read request, reads the
received data of the designated length transmitted by the external
device.
The receive-completion data length can be set within the buffer
memory area allocated for the no-protocol receive.
Advertisement
Table of Contents
