Control Contents Of Dc Code Control; Dc1/Dc3 Transmission Control, Dc1/Dc3 Reception Control - Mitsubishi Electric MELSEC iQ-R Series User Manual

11.2

Control Contents of DC Code Control

This control uses C24 transmission control data to inform a target device whether or not host station is ready to receive data
and the valid range of the transmitted/received data.
The four types of C24 DC code control shown below are available. These control functions can be used simultaneously.
• DC1/DC3 transmission control
• DC1/DC3 reception control
• DC2/DC4 transmission control
• DC2/DC4 reception control

DC1/DC3 transmission control, DC1/DC3 reception control

C24 informs the target device whether or not host station is ready to receive data by transmitting the DC1 and DC3 signals,
and checks whether or not the target device is ready to receive data by receiving the DC1 and DC3 signals.
• DC1: Control data that notifies the target device that C24 is ready to receive data
• DC3: Control data that notifies the target device that C24 is not ready to receive data
Ex.
(Terminate)
Data 1-1
Target device
CPU module D
C
3
DC1/DC3 transmission control and free OS area specification
The control contents and the free OS area specification are the same as those of the DTR control. (Page 237 C24 DTR
control contents and free OS area specification)
C24 operates as shown below depending on the capacity of free OS area.
• Free area is 64 bytes (default) or less: DC3 transmission (reception disabled)
• Free area is 263 bytes (default) or more: DC1 transmission (reception enabled)
Target device
CPU module
■Remarks
• The receive data clear processing clears the data stored in the OS area. (The receive area on the buffer memory is not
cleared.) (Page 67 Receive data clear)
• If more data is received when the free area of the above mentioned OS area is 0 bytes, an SIO error occurs and the data
received until a free area is available is ignored. At that time, the SIO signal is turned ON. (Page 466 Hardware
information communication error "SIO" occurs)
(Restart)...Continue
Data 1-2
D
C
1
Data
D
C
3
11 DATA COMMUNICATIONS USING DC CODE TRANSMISSION CONTROL
D D
C C
3 1
Data 2-1 Data 2-2
(Terminate) (Restart)...Continue
Data
D
C
1
11.2 Control Contents of DC Code Control
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