Mitsubishi MELSEC Q Series Reference Manual page 307

3 - 247
3 WHEN COMMUNICATING USING THE QnA COMPATIBLE 3E/3C/4C FRAMES OR 4E FRAME
(2) Execution procedure on the external device side
(3) The following describes the timing charts when an on-demand
transmission request was issued.
(a) In case of full-duplex communication
When the C24 is receiving data:
The C24 does not transmit any on-demand data is completed before
transmitting a response message (STX to) in reply to the command
message (ENQ to).
E
External device (Command
N
side
message)
Q
Programmable controller CPU side
When the C24 is transmitting data:
The C24 does not transmit any on-demand data until the transmission of a
response message (STX to) in reply to a command message (ENQ to) from
the external device is completed.
E
(Command
External device
N
side
message)
Q
Programmable controller CPU side
On-demand data
S
(Response
T
message)
X
ONDEMAND
On-demand data
S
(Response
T
message)
X
ONDEMAND
3- 247