Rockwell Automation 1785-Lx0C15 ControlNet PLC-5 Programmable Controllers User Manual - Manual (Page 43)

1785-UM022C-EN-P - February 2008
Planning to Use Your ControlNet PLC-5 Processor 2-5
The ControlNet system places your scheduled transfers in the first
part of each Network Update Interval (NUI). Time is automatically
reserved for network maintenance. Unscheduled transfers are
performed during the time remaining in the interval.
Unscheduled messaging on a ControlNet network is
non-deterministic. Your application and your configuration—number
of nodes, application program, NUT, amount of scheduled bandwidth
used, etc.—determine how much time there is for unscheduled
messaging.
Important: The ControlNet network reserves time for at least one
maximum-sized unscheduled transfer per NUI.
Depending on how much time there is for unscheduled
messaging, every node may not have a chance to send
unscheduled data every NUI.
You reserve a
specific amount
of time for all
scheduled
operations
Any time remaining is used
for unscheduled operations
The system
reserves time
for network
maintenance
One occurrence of the NUT is a NUI
. . . . . .