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Overview Section 7-1
7-1-2 Specifications
Send/Receive Message Frames for No-protocol Communications
Note 1. For multiple start codes, the first start code is enabled.
2. For multiple end codes, the first end code is enabled.
Item Description
Communications
mode
Full-duplex
Messages (commu-
nications frame
structure)
Set either of the following types in the Setup Area in the allo-
cation DM Area.
1. Data only (without start code and end code)
2. Start code + data
3. Data + end code
4. Start code + data + end code
5. Data + CR + LF
6. Start code + data +CR + LF
Set in allocated DM Area
(The start code can be included by setting to between 00 and
FF hex, and the end code can be included by setting to
between 00 and FF hex. To exclude the end code, set the
number of receive data bytes.)
Start code None, or 00 to FF hex
End code None, 00 to FF hex, or CR + LF
Number of
receive data
bytes during
reception
Set the number of receive data bytes between
1 and 256 bytes (according to the DM Area
settings) when frame structure 1 or 2 above is
used.
Sending messages • Serial Communications Board: TXD(236) instruction
• Serial Communications Unit: TXDU(256) instruction
Receiving messages • Serial Communications Board: RXD(235) instruction
• Serial Communications Unit: RXDU(255) instruction
Maximum message
length
Sending and receiving: Up to 259 bytes including the start
code and end code (up to 256 bytes excluding start/end
codes)
Data conversion No conversion
Communications
protocol
None
Message delay time When the TXD(236) or TXDU(256) instruction is executed,
after the send delay time, the data is sent from the port.
0 to 300 s (0 to 300,000 ms)
(Can be set in 10-ms units, depending on the DM Area set-
tings)
Receive counter The number of data bytes (0 to 256) received at the port can
be counted.
Reception buffer
clear timing
The reception buffer is cleared immediately after executing the
RXD(235)/RXDU(255) instruction
Start
Code
End code
No Yes CR+LF
No
Yes
Data
256 b
tes max.
Data
256 bytes max.
Data
256 b
tes max.
Data
256 bytes max.
Data
256 bytes max.
Data
256 b
tes max.