7DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL

(4)Transmission: invalid, reception: invalid

MELSEC-Q

 

 

2)-1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E

 

Arbitrary data

Sum check

 

 

 

 

 

N

 

 

 

External device

 

 

Q

 

 

 

code

Ignores the receive

 

 

 

 

 

 

 

 

 

data of 1)-1.

 

Q series C24

E

 

 

 

 

 

 

 

Generates a simultaneous

 

 

 

 

Sum check

 

 

transmission error.

 

Arbitrary data

 

 

 

 

N

 

 

 

Ignores the receivedata of 2)-1.

 

Q

 

 

 

 

code

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1)-1

 

 

 

 

 

 

 

 

 

REMARK

Time-check timer 1 (response monitoring time) shown in the illustration is described in Section 6.2 of User's Manual (Application).

POINT

When the transmission control (see Chapter 9 of User's Manual (Application)) is performed, and the simultaneous transmission data valid/invalid designation sets that the receive data is valid and transmission data is valid, the Q series 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)

•If the Q series C24 receives a terminate transmission request (DC3 received/DSR signal OFF) from the external device during message transmission, it terminates data transmission.

•When the Q series C24 receives the ready to send signal (DC1 received/DSR signal ON), it restarts data transmission.

2)Message reception

•If the Q series 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/DSR signal OFF), it transmits the response message after it receives the ready to send signal (DC1 received/DSR signal ON) from the external device.

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