Tag guidelines for produced or consumed data – Rockwell Automation 1734-AENTR EtherNet/IP Network Configuration User Manual User Manual

Page 63

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Rockwell Automation Publication ENET-UM001L-EN-P - March 2014

63

Interlocking and Data Transfer between Controllers Chapter 6

You must complete these tasks before Logix5000 controllers can share tags over
an EtherNet/IP network:

Set the IP addresses and other network parameters for each EtherNet/IP

communication module.

Connect all wiring and cabling.

Configure a communication driver (such as AB-ETHIP-1) for the

programming workstation.

Tag Guidelines for Produced
or Consumed Data

To properly organize tags for produced or consumed data (shared data), follow
these guidelines.

IMPORTANT

If you are sharing tags between ControlLogix controllers and the
controllers are sharing only tags, not sending messages, set the
communication format of the 1756-ENBT, 1756-EN2F, 1756-EN2T,
1756-EN2TR, 1756-EN2TXT, 1756-EN3TR, 1756-EN2TSC and
1756-EN2TRTXT module to None.

Table 10 - Guidelines for the Organization of Tags

Guideline

Details

Create the tags at the
controller scope.

You can share only controller-scoped tags.

Use one of these data types:
DINT
REAL
array of DINTs or REALs
user-defined

To share other data types, create a user-defined data type that contains the

required data.

Use the same data type for the produced tag and corresponding consumed

tag or tags.

Limit the size of the tag
to

 500 bytes.

If transferring more than 500 bytes, create logic to transfer the data in packets.
A size of < 125 DINT words will keep total bytes within 500. This helps reduce
the total number of packets for transactions.
If producing several tags for the same controller:

Group the data into one or more user-defined data types. This method uses

fewer connections than does producing each tag separately.

Group the data according to similar update intervals. To conserve network

bandwidth, use a greater RPI for less critical data.

For example, you could create one tag for data that is critical and another tag for
data that is not as critical.

Combine data that goes to the same
controller.

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