Omron CJ1W-EIP21 用户手册

There are two kinds of IP addresses, private and global.

• Global addresses: These are IP addresses that connect directly to the

Internet. Allocated by application to NIC, each
address is unique in the world, and as many as
4.3 million can be allocated worldwide.

• Private addresses: These are IP addresses for Intranet (LAN) use, and

cannot connect directly to the Internet. Frames that
include private IP addresses are restricted by the
router from being sent outside the LAN.

Generally, as shown below, global addresses in the intranet are allocated only
to IP routers (such as broadband routers) interfacing with the Internet. All
other nodes in the intranet, including the EtherNet/IP Unit or built-in EtherNet/
IP port, are allocated private addresses.

A global address is required for the IP addresses of the EtherNet/IP Units and
built-in EtherNet/IP port when the following communications services are
used over the Internet.

• FINS communications services

• Explicit message communications services

Intranet

Personal computer, 
CX-Programmer, etc.

Ethernet (EtherNet/IP)

PLC

Firewall

IP router

Private address

Internet

Global address 
(required)

Intranet

Private address

IP router

Global address

Private address

Firewall

Ethernet (EtherNet/IP)

PLC

PLC

Private address

Private address

Not output to Internet

Personal computer, 
CX-Programmer, etc.

Not output to Internet

Private address