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Serial Communications Section 6-1
Procedure
Message Frame
Formats
Data can be placed between a start code and end code for transmission by
TXD(236) and frames with that same format can be received by RXD(235).
When transmitting with TXD(236), just the data from I/O memory is
transmitted, and when receiving with RXD(235), just the data itself is stored in
specified area in I/O memory.
Up to 256 bytes (not including the start and end codes) can be transferred
each time TXD(236) or RXD(235) are used. The start and end codes are
specified in the System Setup.
Message Frame Formats for No-protocol Mode Transmission and Reception
• When more than one start code is used, the first start code will be valid.
• When more than one end code is used, the first end code will be valid.
• If the data being transferred contains the end code, the data transfer will
be stopped midway. In this case, change the end code to CR+LF.
Note The transmission of data after the execution of TXD(236) can be delayed by a
specified transmission delay time, as shown in the following diagram.
Make the System Setup settings from the
CX-Programmer (e.g., set the serial
communications mode to Non-procedural
and set the other communications
conditions.)
Refer to the CX-Programmer
Operation Manual.
Power OFF
Connect the Coordinator Module and the
general-purpose external device using
RS-232C
Power ON
FQM1 → General-purpose
external device
Execute TXD.
General-purpose external
device → FQM1
Execute RXD.
Item End code setting
No Yes CR+LF
Start code
setting
No
Ye s
Data
256 b
y
tes max.
ED
Data
256 b
y
tes max.
CR+LF
Data
256 bytes max.
ST
Data
256 bytes max.
ST
ED
Data
256 bytes max.
ST CR+LF
Data
256 bytes max.