User manual

Publication 1734-UM011A-EN-P - February 2004
About the 1734-AENT Adapter 1-7
from more than one I/O module into a single block of data sent over a single
connection at the same data rate.
Rack optimized connections reduce the total number of connections needed
to transfer data when using many I/O modules in a system. The following
example illustrates the benefit of rack optimized connections.
Assume you have set up a system that contains 8 discrete I/O modules
interfaced to a 1734-AENT adapter. If you use direct connections to transfer
data to each of the these I/O modules, you need 8 connections to transfer all
of the data, one to each of the 8 I/O modules. If you use a rack-optimized
connection to transfer the data, you only need a single connection – the
connection to the 1734-AENT adapter.
See the EtherNet/IP Performance and Application Guide, publication number
ENET-AP001, for more information on connections.
Mix Rack Optimized and Direct Connections
You can mix communication formats for different I/O modules
communicating through the same adapter. I/O modules set up to use rack
optimization will communicate at the rate of the RPI configured for the
1734-AENT adapter. I/O modules configured for direct communication will
communicate at their own set RPIs and ignore the 1734-AENT adapter’s RPI.
IMPORTANT
Although rack optimized connections offer an efficient
way to use resources, there are a few limitations on their
use:
• You can only use rack optimized connections to
send data to and from discrete I/O modules.
Analog or speciality I/O requires direct
connections.
• All data is sent at the same time at the RPI rate of
the 1734-AENT adapter.