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5. NON PROCEDURE
PROTOCOL
COMMUNICATION
MELSEC QnA
5.7
User Frame
5.7.1
What is a user frame?
A user frame is the data list part the message exchanged with the opposite device. It is written to
the QC24 buffer memory (or QC24 internal EEPROM) by the user beforehand and used to send
and receive data.
The user can communicate using a message format matched to the specifications of the external
device by adding a header frame and trailer frame to the data sent and received using the dedi-
cated protocol on-demand function and the non procedure protocol.
\
I
TraileTframe
a
User frame transmission control procedure
[Send]
QC24
[Receive]
QC24
(No user
frame)
(User
Receive data
'1
QC24
(User frame)
(from 1 st)
Output frame
Nos. are
wrltten, beginning
sequentially
from the top.
,
:
Send
5
-
20
No. 8001 user
frame data length
(word unlts)
-Frame
No. 8002 user
frame data length
(word units)
i
'1
: The receive data wlth the user frame removed
IS
stored to the receive buffer.
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