Rockwell Automation 5720 DriveLogix System - Manual (Page 44)

Publication 20D-UM002C-EN-P - November 2003
2-10 What Is DriveLogix?
The communication module you select determines the number of connections
you have available for I/O and messages:
How you configure connections determines how many remote devices a
communication card can support. If you have two communication cards, use
one for messaging (e.g. HMI) and the other for control of I/O. While one card
can support both functions, performance can improve by separating these
functions onto separate cards.
Determining Connections
for Produced and
Consumed Tags The DriveLogix controller supports the ability to produce (broadcast) and
consume (receive) system-shared tags. Produced and consumed tags each
require connections. Over ControlNet, produced and consumed tags are
scheduled connections.
This communication card: Supports this number of connections:
1788-CNx 32 connections–the maiximum number of scheduled
connections is dependent on the RPI:
The remaining connections (or all 32, if you have no
scheduled connections) can be used for unscheduled
connections
1788-ENBT 32 connections - can be used for explicit and implicit
connections
(all 32 connections are any combination of remote
I/O, produce/consume, and messaging connections)
RPI
(with 5 ms NUT) Max Scheduled
Connections
5 ms 3
10 ms 6
20 ms 13
40 ms 20
This type of tag: Requires these connections:
produced By default, a produced tag allows two other controllers to consume the tag, which means
that as many as two controllers can simultaneously receive the tag data. The local
controller (producing) must have one connection for the produced tag and the first
consumer and one more connection for each additional consumer (heartbeat). The default
produced tag requires as many connections as there are consumers for the produced tag.
For example, if the 3 consumers will consume the produced tag, it requires 3 connections.
As you increase the number of controllers that can consume a produced tag, you also
reduce the number of connections the controller has available for other operations, like
communications and I/O.
consumed Each consumed tag requires one connection for the controller that is consuming the tag.