Connections and wiring, Wiring considerations, Network wiring – KMC Controls BAC-14xx36 Series FlexStat User Manual

Page 2: Ms/tp eol (end-of-line) termination, Connections and wiring 2, Wiring considerations 2 network wiring, Caution

BAC-12xx36/13xx36/14xx36 Series FlexStat

Installation Guide, Rev. C

Connections and Wiring

EOL On

Off

Illustration 2—MS/TP Network End-Of-Line Termination

Illustration 3—BAC-12xxxx EOL/Pull-Up Switch Positions

Wiring Considerations

• Because of the many connections (power,

network, inputs, outputs, and their respective

grounds or switched commons), be sure wiring

is well planned before installation of conduit!

• Make sure that conduit for all wiring has ad-

equate diameter for all necessary wiring. Using

1-inch conduit and junction boxes is recommend-

ed! 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.

• To prevent excessive voltage drop, use a conduc-

tor size that is adequate for the wiring length!

Allow plenty of “cushion” to allow for tran-

sient peaks during startup.

• Using multiple conductor wires for all inputs

(e.g., 8 conductor) and outputs (e.g., 12 conduc-

tor) is recommended. Grounds for all the inputs

can be combined on one wire.

CAUTION

To avoid damage from ground loops and other
communication issues in networked FlexStats,
correct phasing on MS/TP network and power
connections on ALL the networked controllers is
critically important.

Network Wiring

For Ethernet or IP communications, plug an Ethernet

cable into the RJ-45 jack on the back of the FlexStat.
For MS/TP communications, connect the –A terminals

in parallel with all other –A terminals on the network

and the +B terminals in parallel with all other +B termi-

nals. (See Illustrations 2 and 5.) Connect the shields of

the cable (Belden cable #82760 or equivalent) together

at each device. Use a wire nut or the S terminal in KMC

BACnet controllers. (FlexStats, however, do not have

an S terminal.) Connect the cable shield to a good earth

ground at one end only.

NOTE: The S terminal in KMC controllers is

provided as a connecting point for the

shield. The terminal is not connected to the

ground of the controller. When connecting

to controllers from other manufacturers,

verify the shield connection is not

connected to the controller’s ground.

For more information on principles and good practic-

es when connecting an MS/TP network, see Planning

BACnet Networks (Application Note AN0404A).

MS/TP EOL (End-Of-Line) Termination

The controllers/thermostats on the physical ends of

an EIA-485 wiring segment must have end-of-line

termination installed for proper network operation.

(See Illustrations 2 through 4.) If a FlexStat is at the

physical end of the MS/TP network line, set both the

EOL termination switches to On (to the right/up)

on the back of the circuit board. If not on the end,

ensure that both switches are Off (left/down).

10K

Ω

0-12 V

Input Pull-Up Switches

OFF

Switch

Pushed

Right

IN2

IN3

IN4

IN7

IN8

IN9

NOTE: 10K

Ω

inputs

are configurable for
Type II or Type III
thermistors in
FlexStat’s menu.

NOTE: EOL = End
Of Line of BACnet
MS/TP network.

EOL Switches

Switch

Pushed

Left

Illustration 4—BAC-13xxxx/14xxxx Switch Positions

10K Ohm

0-12 VDC

Input Pull-Up Switches

EOL

Switches

OFF

Switch Pushed Up

Pushed Down