Mitsubishi MELSEC L Series User Manual page 196
Communication module
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Also See for MELSEC L Series:
- User manual (418 pages) ,
- Programming manual (1296 pages) ,
- Reference manual (532 pages)
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(1) In the DC1/DC3 transmission/reception control, the state of the Q series C24 is
(2) DC1 is not transmitted to the external device.
(2) DC2/DC4 transmission control, DC2/DC4 reception control
7 - 5
REMARKS
• "Receive data clear" described in the User's Manual (Basic) clears the data stored
in the OS area.
• If more data is received when the vacant OS area mentioned above is 0 bytes, an
SIO error is generated and the data received until the OS area becomes vacant is
ignored. At this time, the SIO LED is turned on. (Refer to the User's Manual
(Basic).)
(b) Q series C24 DC1/DC3 reception control contents
1) When the Q series C24 receives DC3 from the external device, it
terminates data transmission.
The sequence program cannot read the received DC3 signal.
2) When the Q series C24 receives DC1 from the external device, it
restarts data transmission.
(The Q series C24 resumes transmission from the data terminated on
DC3 reception.)
The sequence program cannot read the received DC1 signal.
External device
Q series C24
3) Once DC1 is received, subsequent DC1 are ignored and are removed
from the receive data.
POINT
as follows at the time of power-on, reset or mode switching of the CPU, or the
UINI instruction execution.
• This is the same state as when DC1 was transmitted.
• The same state as when DC1 was received even if DC1 is not received from
the external device.
The Q series C24 encloses the send data from the local station in the DC2 and
DC4 codes and transmits it to the external device and processes the data
received from an external device enclosed in the DC2 and DC4 codes as valid
data.
DC2...Control data that informs the external device that the data following it is
the start of the valid data
DC4...Control data that informs the external device that the data immediately
preceding it is the end of the valid data
(Example)
DC2
External device
Programmable
controller CPU
7 DATA COMMUNICATIONS USING DC CODE TRANSMISSION CONTROL
D
C
3
Data
DC4
Data
DC2
D
C
1
Data
DC4
Data
DC2
Data
7 - 5
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