Rockwell Automation 1757-SWKIT5100 ProcessLogix R510.0 Installation and Upgrade Guide - Manual (Page 254)

Publication 1757-IN510A-EN-P - October 2003
11-14 Performance and Capacity Specifications
• The maximum number of nodes permitted on the Supervisory
ControlNet (UMAX) is 24. This permits 10 redundant controllers,
1 redundant Server pair, plus 2 spare nodes.
• The maximum number of nodes permitted on the Supervisory
Ethernet is 12. This permits 10 non-redundant controllers and 1
redundant Server pair.
• The maximum number of nodes permitted on the I/O
ControlNet (UMAX) is 20. With the exception of planning for the
future upgrade of non-redundant controllers to redundant
controllers, unused node addresses may be utilized by Stations,
1757-FIM-Only Chassis, or other appropriate nodes.
Connection Limits
Processing power and memory are finite. CNB modules, for example,
are limited to
64 connections. The 1784-PCIC card is limited to 128
connections.
Node Processing Load Limits
Processing power of nodes of the network is finite. Usually the
“highest” node in the topology processes the most. A downlink CNB
module in a Controller Chassis can process I/O from
24 unscheduled
or 64 scheduled IOMs, requiring multiple CNBs when communicating
with more than 24 unscheduled. The multiple CNBs can be
configured in parallel to a single I/O Net or to physically separate I/O
Nets.
Communications Load Limits
Bandwidth of the network is finite. Some of this bandwidth must be
used for “housekeeping” functions. Message overhead also consumes
bandwidth.
Limits expressed herein are largely derived from the above types of
constraints.