BAC-19xxxx FlexStat Application Guide 14 AG200824A
• Use external junction boxes above the ceiling
or in another convenient location as needed
to make connections that run to the FlexStat’s
junction box.
• Using multiple conductor wires for all inputs
(e.g., 8 conductor) and outputs (e.g., 12
conductor) is recommended. Grounds for all
the inputs can be combined on one wire.
Ethernet Network Wiring Considerations
• For BAC-19xxxxCE models (only), plug an
Ethernet patch cable into the back of the
FlexStat.
• The Ethernet patch cable should be T568B
Category 5 or better and a maximum of 328
feet (100 meters) between devices.
MS/TP Network Wiring Considerations
• Use 18 gauge, twisted-pair, shielded cable with
capacitance of no more than 51 picofarads
per foot (167 pf/m) for all network wiring.
Log in and see the EIA-485 Network Wire
Recommendations Technical Bulletin for
recommendations. For principles and good
practices when connecting an MS/TP network,
see Planning BACnet Networks (Application
Note AN0404A).
• To maintain critical communications in case of
an open conductor on the network cable, use
redundant wiring routed separately to enhance
reliability.
• Connect no more than 128 addressable
BACnet master devices (total) to one MS/
TP network. The devices can be any mix of
controllers or routers. (Up to 127 slave devices
can also be connected.)
• Limiting the MS/TP network size to no more
than about 30 controllers will optimize network
performance.
• If the network has more than 31 MS/TP
devices or if the cable length exceeds 4,000
feet (1,220 meters), use a KMD-5575 repeater
(on an MS/TP-only network if the baud rate on
the network is no higher than 38.4K baud) or
a faster BAC-5051E router with an Ethernet
network. For each network segment, connect
the shields to a good earth ground at only
one end of the segment; tape back the shield
ground at the other end. Generally, use no more
than four KMD-5575 repeaters per MS/TP
network.
• Use a KMD-5567 surge suppressor where a
cable exits the building.
• Avoid possible ground loops. See Avoiding and
Troubleshooting Ground Loops Application
Guide.
• For troubleshooting wiring, see Wiring Issues
on page 23 and the MS/TP Troubleshooting
Using a Multimeter - Bifurcation video and
downloadable troubleshooting guide.
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