Automation Components, Inc.
2305 Pleasant View Road | Middleton, WI 53562
Phone:
1-888-967-5224 |
Website:
workaci.com
Page 1
FIGURE 1:
ENCLOSURE
DIMENSIONS
BACnet / Modbus AVERAGING SERIES
Installation & Operation Instructions
Phone:
1-888-967-5224
Website:
workaci.com
GENERAL INFORMATION
The BACnet MS/TP / Modbus RTU Averaging Series
sensor is designed for use with electronic controllers
in commercial heating and cooling building manage-
ment systems. The ACI BACnet MS/TP / Modbus RTU
Averaging Series sensor monitor the average
temperature in commercial HVAC ductwork and
provides a better average temperature of the air
inside the duct compared to a single point duct
sensor. Averaging sensors are sold in either Copper
or Flexible Averaging variations. The Copper
Averaging sensors include a continuous sensing
element, which covers the entire length of the probe.
The Flexible Averaging sensor has either 4 or 9
sensing points depending on the length. It uses
BACnet MS/TP or Modbus for RTU for physical
connection to a BAS or controller, has dip switches to
set addresses and baud rate, parity and stop bits
(Modbus RTU only), and has on board end-of-line
termination. There is no analog output.
WIRING INSTRUCTIONS
The BACnet MS/TP /Modbus RTU Averaging Series
temperature sensor has a depluggable terminal
block located on the front of the PCB. For ease of
wiring, we recommend removing the block, wiring,
and reattaching before mounting. 16 to 22 AWG
two conductor shielded cable is recommended for
powering the sensors.
ACI recommends using Belden 3105 or compatible
cable for RS-485 communication wiring. This wire has
120 ohm input impendence. The terminal blocks
allow for (1) or (2) wires to be connected in each
position for daisy chaining. Daisy chain the RS-485
wiring and do not use “Star” or “T” wiring. Avoid
running communication wires next to AC line
voltage wires. These can be sources of noise that can
affect signal quality.
3.60"
(91.44 mm)
2.25"
(57.15 mm)
4.79"
(121.55 mm)
2.35"
(59.80 mm)
PRECAUTIONS
• Remove power before wiring. Never
connect or disconnect wiring with power
applied.
• It is recommended you use an isolated
UL-listed class 2 transformer when powering
the unit with 24 VAC. Failure to wire the
devices with the correct polarity when
sharing transformers may result in damage
to any device powered by the shared
transformer.
• If the 24 VDC or 24VAC power is shared with
devices that have coils such as relays,
solenoids, or other inductors, each coil must
have an MOV, DC/AC Transorb, Transient
Voltage Suppressor (ACI Part: 142583), or
diode placed across the coil or inductor. The
cathode, or banded side of the DC Transorb or
diode, connects to the positive side of the
power supply. Without these snubbers, coils
produce very large voltage spikes when
de-energizing that can cause malfunction or
destruction of electronic circuits.
MOUNTING INSTRUCTIONS
Drill a 3/8" (9.53 mm) hole in the duct. Gently uncoil
the copper tubing and insert the averaging
element through the hole until the foam pad is
tight to the duct. The sensor should then be strung
in a criss-cross pattern throughout the duct using
the mounting clips provided - see
FIGURE 5
(P.3)
.
Use a pattern that covers the greatest surface area
of the duct to ensure that there is no stratification.
When bending the copper tubing, be careful that
you use a gradual bend and that you
DO NOT
kink
the copper tubing. Bends should be a minimum of
2” (50.8 mm). Each unit includes nylon wire ties
and mounts for mounting. Optional copper
capillary (ACI Item #
130525)
or universal plastic
mounting clips (ACI Item #
145421
) can be
ordered. Plastic mounting clips will help insulate
the copper sensing element from the metal duct.
The capillary clips help avoid kinks when bending.
When using Flexible averaging, do not cover the
heatshrink that is located throughout the sensor
(sensing points).
Drill pilot holes for the (2) mounting screws. Use the enclosure flange as a guide, or use the
dimensions listed below to measure out. Now fasten and insert (2) screws #8 x 3/4" TEK (provided and
recommended) through the mounting holes in the flange and tighten until the unit is held firmly to
the duct. Make sure the foam pad is tight to the duct to eliminate any possible air leaks.
For optimal temperature measurement, follow these tips:
•
Mount coil horizontal for vertical stratification.
•
Mount coil vertical for horizontal stratification.
•
The sensor must be spread evenly over the full duct.
•
The entire length of the sensor coil must be installed completely inside the duct. Do not have any part of
the sensor exposed to exterior air.
•
When installing the sensor near air-handling units, place the sensor downstream from the fan discharge.
The stratified airstream will be more uniform across the duct cross-section. If the air is not well-mixed, the
reading may be inaccurate.
•
If UV Lights are installed in duct, do not use Flexible Averaging. There is no UV protectant on outer cable
jacket. Copper averaging must be used in this situation.
FIGURE 2:
LAYOUT
DIP SWIT
CH
BAU
D
ADDRESS
OFF
ON
PA
R
SW4
BAC
NET
MOD
BUS
RESET
BUTTON
END OF LINE
TERMINATION
LED
EN
DIS
D+
D-
GN
V
64
32
16
8
4
2
1
4
2
1
1
ON
1
2
2
3
4
TERMINAL
BLOCKS
Version: 2.0
I0000932
