1756-wp002a-en-p - produce data over remote ethernet_ip subnets

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Produce Data over Remote EtherNet/IPSubnets

Configure multicast

addressing for EtherNet/IP

modules via MSG

instructions to support

producing data over remote

EtherNet/IP subnets



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Produce Data over Remote EtherNet/IP Subnets

The default configuration for Logix5000 control systems toproduce data and control I/O over EtherNet/IP networks

supports only the local subnet.

This local-subnet limitation is due in part to the default TTL(Time to Live) value in the firmware for the EtherNet/IPcommunication modules. The TTL value is included in the IPpacket when a communication path crosses a subnet. Therouter decrements the TTL value each time the communicationpath crosses to another subnet. You can continue to cross toother subnets until the TTL value equals 1. The default TTLvalue is 1, thus limiting communication devices to only the localsubnet.

You can use a MSG instruction to increase the TTL value toallow communication to multiple remote subnets. This sameMSG instruction also configures the appropriate multicastaddresses for the remote communication.

The local ControlLogix controller

controls EtherNet/IP I/O on a local

subnet via a 1756-ENBT module.

The local ControlLogix controller can

produce/consume data with the

controller on the remote subnet, as well

as control I/O on the remote subnet

local subnet

remote subnet

Produce Data over

EtherNet/IP

router



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For the local controller to produce data to a remote subnet,configure multicast addresses for that communication module.

For the local controller to control I/O on a remote subnet,configure multicast addresses for both the scanner and adapter modules.

Once a remote subnet connection is established, other localconsumers can join the connection. Also, remote consumerscan join a connection initiated by a remote subnet consumer.

You only have to configure multicast addresses in modules thatproduce data to remote subnets. For produced/consumed tags,

you configure multicast addresses in the producingcommunication module. For remote control of I/O, you configuremulticast addresses in both the local scanner and the remoteadapter communication modules.

To configure multicast addresses, you:

1. Create a user-defined structure to contain the multicastinformation for the module.

2. Send the multicast configuration data to the module via a

MSG instruction.

The module stores the configuration data sent by a MSGinstruction in non-volatile memory. You only need tosuccessfully execute a MSG configuration instruction once.The module retains the configuration data through power cycles to the module.

3. Reset the module to make the configuration take affect.

You only need to reset the communication module once after

successfully sending the multicast configuration data.

Configure Multicast

Addressing



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Create the User-Defined Structure

The multicast configuration data you need to send to thecommunication module is best organized as a user-definedstructure:



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where:

Member: Data Type: Description:EnableOffSubNet SINT 0 = disable remote subnet multicast connections;

1 = enable remote subnet multicast connections

TTL_Value SINT TTL value for remote subnet communications.If EnableOffSubNet = 0, TTL_Value cannot be greater than 1.

Num_Mcast INT Number of multicast addresses to allocate, starting atthe address specified by the four McastStartOctetvalues.

You need one multicast address for each CIP

connection. The maximum number of addresses is thenumber of CIP connections supported by thecommunication module.

See the next section “How to Select a Multicast Address.”

McastStartOctet4 SINT 4th octet of the starting multicast address

For example, in the address 239.255.000.001, the 4th octet is 001.

McastStartOctet3 SINT 3rd octet of the starting multicast address

For example, in the address 239.255.000.001, the 3rd octet is 000.

McastStartOctet2 SINT 2nd octet of the starting multicast address

For example, in the address 239.255.000.001, the 2nd octet is 255.

McastStartOctet1 SINT 1st octet of the starting multicast address

For example, in the address 239.255.000.001, the 1st octet is 239.



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If you enable remote subnet connections, you must specify aTTL value and the total number of multicast addresses. The

multicast addresses you specify are used for both local andremote connections.

You can configure multicast addresses for a module and leaveremote subnet connections disabled. This allows you to specify

• specific multicast addresses for use on local connections• more than 32 multicast addresses, which is the current

limit

How to Select a Multicast Address

Multicast addresses should be in the site local scope of 239.255.000.000 through 239.255.255, inclusive. Whilemulticast addresses can be in the range of 224.000.000.000through 239.255.255.255, the addresses between224.000.000.000 and 224.000.000.255 are reserved for routingprotocols and other low-level topology discovery or maintenanceprotocols, such as gateway discovery and group membershipreporting. Multicast routers should not forward any multicastdata with destination addresses in this range,regardless of its TTL value.

Select multicast addresses that do NOT overlap with addresses:• explicitly configured in other modules• generated by modules that have not been configured for

remote multicast connections and are in the range239.192.000.000 through 239.251.255.255, inclusive.

Send Multicast Configuration Data

Use a CIP generic MSG instruction to send the multicastconfiguration data to the communication module.



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On the Configuration tab:

where:

In this field: Enter:Service Type Set Attribute Single

Service Code 10

Instance 1

Class f5

Attribute 64

Source Element tag that contains the multicast configurationdata

This tag is of the user-defined type youdefined to organize the multicast configurationdata.

Source Length 8

On the Communication tab, specify the communication path tothe EtherNet/IP communication module.



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Reset the Communication Module

To reset the communication module, you can cycle power to themodule or use a CIP generic MSG instruction.

If you use a MSG instruction to reset the module, program adelay to make sure the module has time to process theconfiguration data before resetting the module.

Then program a CIP generic MSG instruction to reset themodule.



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On the Configuration tab, select Device Reset for the ServiceType. The other fields are filled in as appropriate.

On the Communication tab, specify the communication path tothe EtherNet/IP communication module.




Ethernet is a trademark of Digital Equipment Corporation, Intel, and Xerox Corporation.

EtherNet/IP is a trademark used under license by ODVA.

Publication 1756-WP002A-EN-P — August 2004 PN 957928-17Copyright © 2004 Rockwell Automation, Inc. All rights reserved. Printed in USA.

Su ersedes Publication 000-0000-0000 — Month, Year

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