404
Serial Communications
Section 8-3
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 20/14 I/O points.
Serial port 1 and 2 are not supported
by CPU Units with 10 I/O points.
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-EL20DR-D
Страница 3: ...CP1L EL20D CP1L EM30D CP1L EM40D CP1L EL EM CPU Unit Operation Manual Produced July 2017...
Страница 4: ...iv...
Страница 10: ...x...
Страница 22: ...xxii...
Страница 34: ...xxxiv Software Licenses and Copyrights 7...
Страница 178: ...144 Connecting the CX Programmer Section 5 1 Click the Connect button to connect and then connection online is completed...
Страница 192: ...158 Trial Operation and Debugging Section 5 3...
Страница 250: ...216 Automatic Clock Adjustment and Specifying Servers by Host Name Section 6 7...
Страница 666: ...632 Trouble Shooting Section 11 7...
Страница 696: ...662 Standard Models Appendix A...
Страница 805: ...771 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Страница 806: ...772 Connections to Serial Communications Option Boards Appendix F...
Страница 836: ...802 PLC Setup Appendix G...
Страница 838: ...804 TCP Status Transitions Appendix H...
Страница 840: ...806 Ethernet Network Parameters Appendix I...
Страница 842: ...808 Buffer Configuration CP1L EL EM Appendix J...
Страница 844: ...810 Ethernet Specifications Appendix K...
Страница 851: ...Index 817 work words 118 write protection 447...
Страница 852: ...818 Index...
Страница 854: ...820 Revision History...
Страница 855: ......