Rockwell Automation 1757-SWKIT5000 ProcessLogix R500.1 Installation and Upgrade Guide - Manual (Page 253)

Publication 1757-IN500A-EN-P - September 2002
Performance and Capacity Specifications 11-13
Since ProcessLogix permits almost totally generalized intercommunications
paths, the two devices can be under or on:
1. the same H1 link,
2. different links of the same 1757-FIM,
3. different 1757-FIMs in the same IO chassis,
4. different IO chassis of the same controller,
5. different controllers of the same server
As the configuration moves from 1, co-residency on the same H1 link, to 2 to
3 to 4 to 5, more nodes and more networks get involved, increasing the load
on each node and network and adding additional delays to the signals.
Therefore, the interacting equipment should be co-located in the pyramid
when the plant instrumentation and control networks are laid out. The number
of communication circuits between points of differing controllers should be
small (less than 2–5% of the total number of circuits.)
System Communications Limits
Communications limits are derived from various capacities. Common
constraints are described below.
Node Address Range Limits
Arbitrarily high limits on a network reduce effective bandwidth and effect
recovery time.
• 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