MITSUBISHI ELECTRIC QJ71C24N - Manual (Page 171)

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MELSEC-Q
7 DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL
1) Starts the local station PLC.
The setting values for GX Developer are stored in the Q series C24.
2) Inputs the user data transmission instruction signal.
3) Executes the BIDOUT instruction after storing the transmission data and the
control data for the BIDOUT instruction in the device.
Data is sent when the BIDOUT instruction is executed.
4) A response message for the data transmission (for normal completion: ACK
message; for abnormal completion: NAK message) is received.
5) When the response is received, the Q series C24 transmission processing
completes and the device that has completed the BIDOUT instruction turns ON.
When the BIDOUT instruction ends abnormally due to the reception of an NAK
message, the complete device +1 (abnormal completion signal) turns ON and the
error code is stored in the control data completion status (S1+1).
(Program example)
When Q series C24 I/O signals are from X/Y00 to X/Y1F:
Transmission data is stored.
Clear the transmission result storage device to 0.
Designate the transmission data count in word units.
(Designate K10 when the unit is bytes.)
The transmission data stored in the designated device is
sent.
After the BIDOUT instruction is executed, the user
designated transmission complete signal (M1) turns ON for
one scan.
Storing the transmission data and writing the transmission
data count in the buffer memory, and issuing a
transmission request to the Q series C24 are all executed
by the PLC CPU.
Designate the number of the interface (CH ) that will
send the data.
Transmission command is converted to pulse.
The completion flag is reset by the external command.