Rockwell Automation 1785-L20C_L40C, D17856.5.14 ControlNet PLC-5 Programmable Controllers User Manual - Manual (Page 31)

Chapter 2
Planning to Use Your ControlNet
PLCĆ5 Processor
2-3
Unscheduled DataĆTransfer Operations on a ControlNet Network
The ControlNet network allows you to use unscheduled messaging when
deterministic delivery is not required. Unscheduled operations include:
unscheduled non-discrete I/O data transfers—through ControlNet I/O
Transfer (CIO) instructions
peer-to-peer messaging—through Message (MSG) instructions
messaging from programming devices
The ControlNet system places your scheduled transfers in the first part
of each Network Update Interval (NUI), time is automatically reserved
for network maintenance, and unscheduled transfers are performed during
the time remaining in the interval.
ЗЗЗЗЗ
ЗЗЗЗЗ ЙЙЙЙЙЙ
ЙЙЙЙЙЙ Д
Д
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
ЗЗЗЗЗ
ЗЗЗЗЗ ЙЙЙЙЙЙ
ЙЙЙЙЙЙ ДД
ДД
. . . . . .
Unscheduled messaging on a ControlNet network is non-deterministic.
Your application and your configuration—number of nodes, application
program, NUT, etc.—help determine how much time there is for
unscheduled messaging.
Important: The ControlNet network reserves time for at least one
unscheduled transfer per NUI.