Omron CJ1W-EIP21 User Manual

8 Message Communications
8-2
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
8-1 Overview of the CIP Message
Communications Service
CIP commands can be sent to devices on the EtherNet/IP network whenever they are required. You
execute CIP_SEND instructions in a program in the NJ-series CPU Unit to send CIP commands, such
as those to read and write data and to receive the responses.
You can use CIP messages from the client to read and write memory in the Controller with the server
without adding any special programming to the user program of the Controller with the server.
8-1-1 Overview of the CIP Message Communications Service
8-1-2 Message Communications Service Specifications
Item Specification
Message type Either of the following can be selected.
CIP UCMM connectionless messages
CIP class 3 connection messages
Execution method CIPSend (Send Explicit Message Class 3) instruction or CIPUCMM
(Read Variable UCMM Explicit) instruction
Data contents Sending required CIP commands and receiving responses
Communications parameters Message type, timeout value, and root path specification
Maximum length per
connection
Non-connection
type (UCMM)
502 bytes
Connection type
(class 3)
502 bytes for Forward_Open
1,994 bytes for Large_Forward_Open
EtherNet/IP
EtherNet/IP
Unit
NJ-series
Controller
CIP response
CIP command
or host computer
EtherNet/IP
Unit
NJ-series
Controller

Omron CJ1W-EIP21 Specifications

General

Brand	Omron
Model	CJ1W-EIP21
Category	Controller
Language	English