Omron SYSMAC CJ - REFERENCE MANUAL 01-2008 Reference Manual page 1013

Serial Communications Instructions
Instructions
TXD(236),
Any of the following can be used.
RXD(235),
No Start or End Code
TXDU(256),
Data
and
RXDU(255)
Only Start Code
Only End Code
Data
PMCR(260)
The following type of frames (messages) can be created
to meet the requirements of the external device.
Header
Communications steps
can be created.
Instructions Mode
TXD(236) No-protocol
and (custom)
RXD(235)
TXDU(256) No-protocol
and (custom)
RXDU(255)
PMCR(260) Protocol macro
974
Communications frames
Start and End Code
CR+LF End Code
Data Data
Start and CR+LF End Code
Data
Address
Error check Terminator
I/O memory
Read/write
Serial port in CPU Unit or Serial Communications Board
CPU Unit
RXD(235)
TXD(236)
Serial Port of Serial Communications Unit (Version 1.2 or later)
Serial Communications unit
TXD
Serial Communications Board (CS Series
Receive
Send
Sends or receives data in one direction only.
A send delay can be set.
Data
Data
Up to 16 steps can be defined for sending
and receiving.
Steps can be changed and retry processing
performed based on responses.
Communications monitoring times can be
set.
Symbols can be read/written for the PLC.
Repeat symbols can be used.
Other.
Communications ports
TXD(236)/
RXD(235)
CPU Unit
TXDU/RXDU
RXD
Serial Communications Unit
only)
Serial Commu-
nications Board
Send
Section 3-24
Function
TXD(236) and RXD(235)
use serial ports on the
CPU Unit or Serial
Communications Boards
(Ver. 1.2 or later).
Serial Communications Unit
Receive