MITSUBISHI ELECTRIC QJ71C24N - Manual (Page 29)

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MELSEC-Q
1 OVERVIEW
(d) It is necessary to create a sequence program for communication control that
conforms to the external device.
(e) Communication can be performed using an user frame by registering the fixed
format portion of the head and tail sections of a message as an user frame.
• When sending data, the Q series C24 adds an user frame to any data
specified by the user.
• When receiving data, the Q series C24 transfers any data excluding the
user frame to the PLC CPU.
Any data format ETX
ETX STX
STX
QJ71E71
RUN
INIT.
OPEN SD
ERR.
COM.ERR
RD
10BASE-T
+12V
12G
10BASE
RS-232
MODE
RUN
ERR.
USER
BAT.
BOOT
CH.2
SDA
SG
SDB
(FG)
RDA
(FG)
RDB
RS-422
/485
CH1.
CH2. CH1.
2
1
3
4
5
6
7
RS-232
USB
Q25HCPU
POWER
MELSEC
PULL
MITSUBISHI
QJ71C24
Any data format
When receiving data
When sending data
(f) It is possible to clear the current reception data without interrupting the
transmission processing by using the dedicated instruction "CSET."
(3) Data communication using the bidirectional protocol
(Details are explained in Chapter 7 and the User's Manual (Application).)
(a) In communication between PLC CPUs and communication with an external
device for which transmission/receive control programming is allowed, data
communication is performed in a sequence of "data transmission and
response receipt".
(b) Error check of received data can be performed using the sum-check code,
while the occurrence of a reception error at an external device can be
checked via an ACK/NAK response.
ENQ
Sum check
code
Any data
ACK
Data length
NAK
Error
code
Sending completed normally
Sending completed
abnormally
QJ71E71
RUN
INIT. OPEN
SD
ERR.
COM.ERR
RD
10BASE-T
+12V
12G
10BASE
RS-232
MODE
RUN
ERR.
USER
BAT.
BOOT
CH.2
SDA
SG
SDB
(FG)
RDA
(FG)
RDB
RS-422
/485
CH1.
CH2. CH1.
2
1
3
4
5
6
7
RS-232
USB
Q25HCPU
POWER
MELSEC
PULL
MITSUBISHI
QJ71C24
(c) ASCII code data can be used for communication using the ASCII-BIN
conversion function.
ASCII-BIN
conversion
Binary
data
QJ71C24
Binary
data
ASCII
data
MODE
RUN
ERR.
USER
BAT.
BOOT
RS-232
USB
Q25HCPU
QCPU