Mitsubishi MELSEC LJ71C24, User Manual

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11 DATA COMMUNICATION USING THE BIDIRECTIONAL PROTOCOL
(4) Transmission: Invalid, Receive: Invalid
C24 side
External device
E
N
Q
E
N
Q
2)-1
1)-1
Ignores the receive
data of 1)-1.
Generates a simultaneous
transmission error.
Ignores the receive data of 2)-1.
Arbitrary data
Sum check
code
Arbitrary data
Sum check
code
REMARKS
Time-check timer 1 (response monitoring time) shown in the illustration is described
in the User's Manual (Application).
POINT
When the transmission control (refer to User's Manual (Application)) is performed
with "Transmission data" set to "Valid" and "Receive data" set to "Valid", the C24
performs message transmission and message reception processing as described
below.
During message transmission processing, time check by timer 1 (response
monitoring time) is performed.
1) Message transmission (1)-1 in the illustration)
• When the C24 receives a terminate transmission request (DC3
received/DR(DSR) signal OFF) from the external device during message
transmission, the C24 terminates data transmission.
• When the C24 receives the ready to send signal (DC1 received/DR(DSR)
signal ON), the C24 restarts data transmission.
2) Message reception
• If the C24 cannot send a response message to the external device in
response to message reception because the external device issued a
terminate transmission request (DC3 received/DR(DSR) signal OFF), the
C24 transmits the response message after it receives the ready to send
signal (DC1 received/DR(DSR) signal ON) from the external device.