Rockwell-automation 1747-AENTR SLC 500 EtherNet/IP Adapter User Manual Manual de usuario descargar pdf (Pagina 21)

Rockwell Automation Publication 1747-UM076C-EN-E - January 2013 15

Configure the Adapter for Your EtherNet/IP Network Chapter 3

When a node needs to communicate with a node on another network, a gateway

transfers the data between the two networks. The figure shows gateway G

connecting Network 1 with Network 2.

When host B with IP address 128.2.0.1 communicates with host C, it knows

from C’s IP address that C is on the same network. In an Ethernet environment,

B can then resolve C’s IP address into a hardware address (MAC address) and

communicate with C directly.

When host B communicates with host A, it knows from A’s IP address that A is

on another network (the network IDs are different). In order to send data to A, B

must use the IP address of the gateway connecting the two networks. In this

example, the gateway’s IP address on Network 2 is 128.2.0.3.

The gateway has two IP addresses (128.1.0.2 and 128.2.0.3). The first must be

used by hosts on Network 1 and the second must be used by hosts on Network 2.

To be usable, a gateway of a host must be addressed using a network ID matching

its own.

Subnet Mask

The subnet mask is used for splitting IP networks into a series of su/jointfilesconvert/1606317/bgroups, or

subnets. The mask is a binary pattern that is matched up with the IP address to

turn part of the Host ID address field into a field for subnets.

EXAMPLE

Take Network 2 (a Class B network) in the previous example and add

another physical network. Selecting the following subnet mask would

add two additional network ID bits, allowing for four physical networks:

11111111 11111111 11000000 00000000 = 255.255.192.0

Network 1

Network 2

128.1.0.1

128.2.0.1 128.2.0.2 128.2.0.3

128.1.0.2

These two bits of the Host ID are used to

extend the netdwork ID.

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 83 84

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Rockwell-automation 1747-AENTR SLC 500 EtherNet/IP Adapter User Manual Manual de usuario Pagina 21