App - 27 App - 27
MELSEC-Q
APPENDIX
Appendix 7.1.2 DC1/DC3 reception control enabled
Transmission of data from a BASIC program is controlled by DC1/DC3 control signals
received from an external device.
If a DC1 control signal is received, data transmission starts or continues.
If a DC3 control signal is received, data transmission is stopped. When a data
transmission is stopped due to the reception of the DC3 control signal, the remaining
data will be sent when a DC1 control signal is received again later.
Channel open 1
(BASIC program)
ZOPEN • • • •
ZSEND • • • •
Communication module
Send buffer
(OS)
Transmission result
External device
Waiting to send
DC3 control signal
DC1 control signal
Data
Data
A
D51H
1 When the communication channel is opened, the status of the send buffer is the same as when a DC1
control signal is received even if the DC1 control signal is not received from the external device.