Communication Data Processing When Simultaneous Transmissions Occur - Mitsubishi Melsec-L Series User Manual

11.3.2 Communication data processing when simultaneous transmissions occur

External device
C24 side
External device
C24 side
1)-1
External device
C24 side
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Examples of the C24 communication data processing for the "Transmission data" and
"Receive data" settings by GX Works2 are explained.
(1) Transmission: Valid, Receive: Valid
2)-1
E
N
Q
E
Arbitrary data
N
Q
1)-1
POINT
When the entire message of 2)-1 was received while transmitting the message of
1)-1 in the illustration:
• The C24 turns ON Receive read request (X3/X4) of 2)-1 after sending all of 1)-1.
(2) Transmission: Invalid, Receive: Valid
2)-1
E
Arbitrary data
N
Q
E
Arbitrary data
N
Q
(3) Transmission: Valid, Receive: Invalid
1)-1
E
N
Arbitrary data
Q
E
N Arbitrary data
Q
1)-1
11 DATA COMMUNICATION USING THE BIDIRECTIONAL PROTOCOL
Arbitrary data
Sum check
code
Sum check
code
Sum check
code
Sum check
code
Sum check
code
1)-2
Sum check
code
Time check
(timer 1)
Ignores the receive
data of 1)-1.
(Generates a simultaneous
A
transmission error.)
C
K
2)-2
1)-2
A
C
K
Time check
(timer 1)
A
C
K
A
C
K
2)-2
Ignores the receive
data of 2)-1.
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