Omron CP1H-CPU - 05-2006 Operation Manual page 366

Serial Communications
Procedure
Message Frame Formats
Start code
No
Yes
ST
Set the PLC Setup from the CX-
Programmer.
(Set the communications mode to
RS-232C and set the parameters.)
Power OFF
Connect the CPU Unit and external device
through the RS-232C port. (Mounting the
RS-232C Option Board in option slot 1 or 2.
Set the DIP switch on the front of
the CPU Unit.
Power ON
PLC External device
Execute TXD(236).
Data can be placed between a start code and end code for transmission by
TXD(236) and data between a start code and end code can be received by
RXD(235). When transmitting with TXD(236), data from I/O memory is trans-
mitted, and when receiving with RXD(235), the data (without start/end codes)
is stored in I/O memory. Up to 256 bytes (including the start and end codes)
can be transferred in no-protocol mode.
The start and end codes are set in the PLC Setup.
The following table shows the message formats that can be set for transmis-
sions and receptions in no-protocol mode.
No
data
256 bytes max.
data
256 bytes max.
• When more than one start code is used, the first start code will be effec-
tive.
• When more than one end code is used, the first end code will be effective.
• 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.
Turn OFF pin 4 to use serial port 1.
Turn OFF pin 5 to use serial port 2.
External device
Execute RXD(235).
End code
Yes
ED
data
256 bytes max.
data
ST ED
256 bytes max.
Section 6-1
PLC
CR+LF
CR+F
data
256 bytes max.
ST data CR+LF
256 bytes max.
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