Rockwell Automation 1756-ENET/B ControlLogix Ethernet Communication Interface Module User Manual - Manual (Page 23)

Publication 1756-UM051B-EN-P - November 2000
About the 1756-ENET/B Module 1-5
Specifying the Requested
Packet Interval (RPI) The RPI is the update rate specified for a particular piece of data on
the network. The RPI can be specified for an entire rack (using a rack
optimized connection) or for a particular module (using direct
connection). When you add a module to the I/O configuration of a
controller, you must enter the RPI as a parameter. ‘This value specifies
how often to produce the data for that module. For example, if you
specify an RPI of 50ms, it means that every 50ms the I/O module
should send its data to the controller or that the controller should send
its data to the I/O module.
RPIs are only used for modules that produce data. For example a local
1756-ENET/B module (i.e., an ENET/B module in the same chassis as
the controller) does not require an RPI because it is not a
data-producing member of the system; it is used only as a bridge to
remote racks.
What’s Next? The following chapter describes how to install the Ethernet module
and connect it to the network.