Rockwell Automation 1756-IF4FXOF2F ControlLogix High-speed Analog I/O Module - Manual (Page 137)

Rockwell Automation Publication 1756-UM005B-EN-P - January 2013 137
Appendix
E
Module Operation in a Remote Chassis
Remote Modules Connected
via the ControlNet Network If a high-speed analog I/O module resides in a remote chassis, the role of the RPI
and the module’s RTS behavior change slightly with respect to sending input data
to the owner.
In a local chassis, the RPI and RTS rates define when a module multicasts input
data as described in
Chapter 2 . If the module is located in a remote chassis,
however, the value of the RPI determines how often the owner-controller
receives it over the network.
When an RPI value is specified for a high-speed analog I/O module in a remote
chassis, in addition to instructing the module to multicast input data within its
own chassis, the RPI also reserves a spot in the stream of data flowing across the
ControlNet network.
Topic Page
Remote Modules Connected via the ControlNet Network 137
Use RSNetWorx Software and Logix Designer Application 140
Configure High-speed Analog I/O Modules in a Remote Chassis 141
IMPORTANT The performance of a high-speed analog I/O module is limited in a remote
chassis. The network cannot effectively accommodate the fastest module
update rates because the size of the data broadcast requires a large portion of
the network’s bandwidth. For maximum module performance, we recommend
you use it in a local chassis.
Also, when you use a ControlLogix high-speed analog I/O module in a remote
chassis, you must use RSNetWorx™ for ControlNet software to configure the
ControlNet network. For more information on how to use RSNetWorx for
ControlNet software, see
page 140 .