4
Control Module Communication
RED LED — Proper operation of the control boards can be
visually checked by looking at the red status LEDs (light-
emitting diodes). When operating correctly, the red status
LEDs should be blinking in unison at a rate of once every
2 seconds. If the red LEDs are not blinking in unison, verify
that correct power is being supplied to all modules. Be sure that
the Main Base Board (MBB) is supplied with the current soft-
ware. If necessary, reload current software. If the problem still
persists, replace the MBB. A red LED that is lit continuously or
blinking at a rate of once per second or faster indicates that the
board should be replaced.
GREEN LED — The MBB has one green LED. The Local
Equipment Network (LEN) LED should always be blinking
whenever power is on. All other boards have a LEN LED
which should be blinking whenever power is on. Check LEN
connections for potential communication errors at the board J3
and/or J4 connectors. Communication between modules is ac-
complished by a 3-wire sensor bus. These 3 wires run in paral-
lel from module to module. The J4 connector on the MBB pro-
vides both power and communication directly to the marquee
display only.
YELLOW LED — The MBB has one yellow LED. The
Carrier Comfort Network (CCN) LED will blink during times
of network communication.
Carrier Comfort Network (CCN) Interface —
The 30GTN,R chiller units can be connected to the CCN if
desired. The communication bus wiring is a shielded,
3-conductor cable with drain wire and is supplied and installed
in the field. The system elements are connected to the commu-
nication bus in a daisy chain arrangement. The positive pin of
each system element communication connector must be wired
to the positive pins of the system elements on either side of it.
This is also required for the negative and signal ground pins of
each system element. Wiring connections for CCN should be
made at TB3. Consult the CCN Contractor’s Manual for fur-
ther information.
NOTE: Conductors and drain wire must be 20 AWG (Amer-
ican Wire Gage) minimum stranded, tinned copper. Individual
conductors must be insulated with PVC, PVC/nylon, vinyl,
Teflon, or polyethylene. An aluminum/polyester 100% foil
shield and an outer jacket of PVC, PVC/nylon, chrome vinyl,
or Teflon with a minimum operating temperature range of
–20 C to 60 C is required. Wire manufactured by Alpha (2413
or 5463), American (A22503), Belden (8772), or Columbia
(02525) meets the above mentioned requirements.
It is important when connecting to a CCN communication
bus that a color coding scheme be used for the entire network
to simplify the installation. It is recommended that red be used
for the signal positive, black for the signal negative, and white
for the signal ground. Use a similar scheme for cables contain-
ing different colored wires.
At each system element, the shields of its communication
bus cables must be tied together. If the communication bus is
entirely within one building, the resulting continuous shield
must be connected to a ground at one point only. If the commu-
nication bus cable exits from one building and enters another,
the shields must be connected to grounds at the lightning sup-
pressor in each building where the cable enters or exits the
building (one point per building only). To connect the unit to
the network:
1. Turn off power to the control box.
2. Cut the CCN wire and strip the ends of the red (+), white
(ground), and black (–) conductors. (Substitute appropri-
ate colors for different colored cables.)
3. Connect the red wire to (+) terminal on TB3 of the plug,
the white wire to COM terminal, and the black wire to the
(–) terminal.
4. The RJ14 CCN connector on TB3 can also be used, but is
only intended for temporary connection (for example, a
laptop computer running Service Tool).
Table 2 — Thermistor Designations
LEGEND
IMPORTANT: A shorted CCN bus cable will prevent
some routines from running and may prevent the unit
from starting. If abnormal conditions occur, unplug the
connector. If conditions return to normal, check the
CCN connector and cable. Run new cable if necessary.
A short in one section of the bus can cause problems
with all system elements on the bus.
THERMISTOR
NO.
PIN
CONNECTION
POINT
THERMISTOR INPUT
T1 J8-13,14 (MBB) Cooler Leaving Fluid
T2 J8-11,12 (MBB) Cooler Entering Fluid
T3
J8-21,22 (MBB) Saturated Condensing
Temperature, Ckt A
T4
J8-15,16 (MBB) Saturated Condensing
Temperature, Ckt B
T5
J8-24,25 (MBB) Cooler Suction Temperature,
Ckt A (EXV Only)
T6
J8-18,19 (MBB) Cooler Suction Temperature,
Ckt B (EXV Only)
T7
J5-11,12 (EXV) Compressor Suction Gas
Temperature, Ckt A (EXV Only)
T8
J5-9,10 (EXV) Compressor Suction Gas
Temperature, Ckt B (EXV Only)
T9
J8-7,8 (MBB) Outdoor-Air Temperature
Sensor or Dual Chiller LWT
Sensors (Accessory)
T10
J8-5,6 (MBB) Remote Space Temperature
Sensor (Accessory)
EXV — Electronic Expansion Valve
MBB — Main Base Board
