![background image](http://html.mh-extra.com/html/omron/c200hw-clk21/c200hw-clk21_operation-manual_742483193.webp)
168
Introduction
Section 6-1
6-1
Introduction
A message service is a command/response system used for data transmis-
sion between nodes on a network, i.e., PLC to PLC, PLC to computer, and
computer to PLC). The message service can also be used to control opera-
tions, such as mode changes. The message service is implemented by send-
ing commands from the user program. The following communications
instructions are used:
SEND and RECV:
Instructions for sending and receiving data.
CMND:
An instruction for sending FINS commands. Some FINS commands
are supported by Controller Link Units, and other FINS commands supported
by the PLC’s CPU Unit.
Message service
SEND/RECV instructions
CMND instruction (FINS commands)
Source
node to
destination
node
PLC to PLC
PLC to
computer
Computer
to PLC
C200HX/HG/HE,
CS/CJ-series, CVM1,
CV-series, or
CQM1H-series PLC
User program
A program is not required for receiving
responses when the PLC executes
SEND and RECV.
SEND
(Com-
mand for
CPU Unit)
C200HX/HG/HE,
CS/CJ-series, CVM1,
CV-series, or
CQM1H-series PLC
(Com-
mand for
CPU Unit)
User program
A program is not required for receiving
responses when the PLC executes
commands.
CMND
(Com-
mand for
Controller
Link Unit)
(Not supported by the
C200HX/HG/HE.)
Command
Command
C200HX/HG/HE,
CS/CJ-series, CVM1,
CV-series, or
CQM1H-series PLC
CS/CJ-series, CVM1,
CV-series, or
CQM1H-series PLC
C200HX/HG/HE,
CS/CJ-series, CVM1,
CV-series, or CQM1H-
series PLC
Computer
A program is required for sending and
receiving data with the computer.
A program is not required for receiving
responses when the PLC executes commands.
Command
SEND
C200HX/HG/HE,
CS/CJ-series, CVM1, CV-series
or CQM1H-series PLC
(The equivalent of SEND/
RECV and CMND are sent
from the computer pro
gram.)
Computer
Command
(Command for
Controller Link
Unit or CPU
Unit)
Programming is required to receive
responses at the computer.
Summary of Contents for C200HW-CLK21
Page 3: ...iv ...
Page 9: ...x ...
Page 12: ...xiii TABLE OF CONTENTS Index 367 Revision History 373 ...
Page 13: ...xiv ...
Page 19: ...xx ...
Page 57: ...32 Application Precautions Section 1 5 Example CX Programmer Response Timeout Setting ...
Page 69: ...44 Message Service Procedure Section 2 2 ...
Page 111: ...86 Constructing Networks with Repeater Units Section 3 4 ...
Page 154: ...129 Setting Data Links Section 5 2 Device Information Setting Data Link Tables ...
Page 261: ...236 Response Codes Section 6 7 ...
Page 297: ...272 Message Delay Times Section 8 4 ...
Page 353: ...328 Handling Precautions Section 9 6 ...
Page 364: ...339 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 365: ...340 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 369: ...344 Standard Models Appendix A ...
Page 391: ...366 Using the Relay Terminal Block Appendix C ...
Page 397: ...372 Index ...
Page 401: ...376 Revision History ...