Installation guide

Network Infrastructure for EtherNet/IP™
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Selecting Components
7.3.6 Broadcast or Multicast Threshold Filters
Switches may have a fixed or user-variable option for restricting the maximum allowed level of broadcast
or multicast traffic. Once the threshold is exceeded, it may turn off the port until the traffic falls below the
threshold level or shut down the port completely based on the vendor’s implementation. This feature can
help lessen the effects of abnormal traffic conditions. For high-speed control applications, the threshold
level must be checked to confirm that it does not interfere with normal traffic.
7.3.7 Additional Functions
The switch functions described above provide an overview of basic capabilities. Appendix A
Recommendations for Ethernet Switches in EtherNet/IP Systems contains descriptions of additional
industrial switch functions, and how they relate to the various types of application scenarios described in
6 Infrastructure Application Scenarios.
7.4 Distributed Enclosures and Environmental Considerations
Commercial switches, routers, and other equipment are fine for the office closet. If, however, commercial
network equipment is to be located on the plant floor, it must be housed in industrial enclosures that are
capable of protecting it from plant-floor environments. Industrial-grade equipment is the better option as
it is designed to withstand harsh conditions. In either case, environmental factors can be critical to reliable
operation, and all equipment should be protected accordingly. Lost or corrupted data is bad enough, but
harsh conditions—especially heat and vibration—can slowly destroy unprotected equipment.
7.4.1 Environmental Specification Considerations
The required specifications for Ethernet devices used in industrial applications are dependent on where
and how the devices are to be mounted. DIN-rail versus rack mounting and the use of 120 Vac versus 24
Vdc power need to be considered. Some additional considerations follow.
7.4.2 Temperature
Industrial manufacturing facilities can contain a wide range of environments, even within the same
facility. The environment outside the enclosure, as well as heat-generating devices within the enclosure,
needs to be considered. Without added environmental conditioning equipment, traditional (commercial)
infrastructure components with 40
o
C to 45
o
C (104
o
F to 113
o
F) ratings should be used in control rooms
or lighter industrial environments away from heat-producing machines or processes.
Cabinet fans or air conditioners may be needed for hot environments or where heat-producing PCs or
motion control devices are mounted in the same enclosure. When mounted near or on heat-producing
machines or processes, and where space, maintenance or other considerations prevent the use of air
conditioners or fans, infrastructure components with PLC ratings of 55
o
C (131
o
F) or higher are available.
Operating humidity specifications of 85% to 95% RH (non-condensing) should be considered for
processing applications where water is present (wood, paper, food, etc.) and in non-air-conditioned plants
in high-humidity locations. In corrosive atmospheres, electronics should be sealed completely to protect
circuits from caustic or acidic vapors that can strip away conductors on printed circuits.