Allen-Bradley ControlNet Compact GuardLogix 1769, User Manual, Page: 35 / 100

Configure a ControlNet Module Chapter 3
The communication format setting also affects the RPI rate.
Table 7 - Communication Formats
Communication Format Function Effect on RPI
Rack-optimized The communication module creates a rack image and
returns I/O data in the rack image to the owner-controller.
This option is available only for digital I/O modules.
Remember that diagnostic I/O modules will not return
diagnostic data when you use this format.
You can specify an RPI that meets this criteria:
• Equal to or greater than the NUT
• In the range permitted by RSLogix 5000 programming
software, for example 2…750 ms
When you set the RPI for a remote ControlNet
communication module, we recommend you use a rate
that is a power of two times the NUT.
For example, if your NUT = 5 ms, we recommend these RPI
values.
Listen-only rack-optimized (not
available on all ControlNet
communication modules)
The communication module creates a rack image and
returns I/O input data in the rack image to the owner-
controller.
The difference between this choice and rack-optimized is
that the I/O data in the rack image is returned to a
controller that does not control the outputs but is listening
only to its input data.
None No RPI is required. The RPI field is dimmed.
4. On the Module Properties dialog box, configure the connection properties
and then click Apply.
Connection Property Action
Requested Packet Interval (RPI) Type the requested packet interval between 2.0…750.0 ms.
If your module uses one of the rack-optimized communication formats, the RPI must be equal
to or greater than the ControlNet Network Update Time (NUT).
Inhibit Module If the module does not need to communicate with the controller, check the checkbox.
or
If the module needs to communicate with the controller, leave the checkbox cleared.
IMPORTANT:
When you test this portion of the system, leave the checkbox cleared.
Major Fault On Controller If Connection Fails While In
Run Mode
If you want the controller to produce a major fault if the connection to the local
communication module fails in Run mode, check the checkbox.
or
If you want the controller to continue operating if the connection to the local communication
module fails in Run mode, leave the checkbox cleared. Use ladder logic to monitor the
connection.
Use Scheduled Connection over ControlNet Check the box if you want to explicitly schedule the network connection.
Note the following:
• The checkbox is enabled when the connection for the module crosses ControlNet and the
module supports unscheduled connections.
• The checkbox is checked and disabled when the connection to the module crosses
ControlNet, and the module does not support unscheduled connections, and therefore,
must be scheduled.
•
The checkbox is cleared and disabled when the connection to the module does not cross
ControlNet, or the connection crosses ControlNet but does not need to be scheduled.
Rockwell Automation Publication CNET- UM001E-EN-P - June 2016
35
NUT = 5m x 2
0
x 2
1
x 2
2
x 2
3
x 2
4
Optimal RPI
values
5 ms 10 ms 20 ms 40 ms 80 ms