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346
Serial Communications
Section 6-3
Procedure
Message Frame Formats
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.
• 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.
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
RS-232C or RS-485. (Mounting the RS-232C or
RS-422A/485 Option Board in option slot 1 or 2.
Set the DIP switch on the front of
the CPU Unit.
Turn OFF pin 4 to use serial port 1.
Turn OFF pin 5 to use serial port 2.
Note
Serial port 2 is not supported by CPU
Units with CPU type L.
Power ON
PLC
→
External device
External device
→
PLC
Execute TXD(236).
Execute RXD(235).
Start code
End code
No
Yes
CR+LF
No
Yes
data
256 bytes max.
data
256 bytes max.
ED
data
256 bytes max.
CR+F
data
256 bytes max.
ST
data
256 bytes max.
ST
ED
data
256 bytes max.
ST
CR+LF
Содержание CP1L - 12-2007
Страница 3: ...iv...
Страница 9: ...x...
Страница 13: ...xiv TABLE OF CONTENTS...
Страница 21: ...xxii...
Страница 33: ...xxxiv Conformance to EC Directives 6...
Страница 65: ...32 Function Blocks Section 1 5...
Страница 428: ...395 Clock Section 6 9...
Страница 429: ...396 Clock Section 6 9...
Страница 523: ...488 Troubleshooting Unit Errors Section 9 4...
Страница 531: ...496 Replacing User serviceable Parts Section 10 2...
Страница 563: ...528 Auxiliary Area Allocations by Function Appendix C...
Страница 611: ...576 Auxiliary Area Allocations by Address Appendix D...
Страница 638: ...603 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Страница 639: ...604 Connections to Serial Communications Option Boards Appendix F...
Страница 669: ...634 Index...
Страница 671: ...636 Revision History...