66
On sensor bus terminal strips, terminal 1 of PSIO module is
connected to terminal 1 of each of the other modules. Termi-
nals 2 and 3 are connected in the same manner. See Fig. 25. If a
terminal 2 wire is connected to terminal 1, system does not
work.
In the 30GX control box, the processor module (PSIO-1),
DSIO-HV, and HSIO are all powered from a common 21 vac
power source (PSIO-1 and HSIO are powered from 24 vac
source on 30HX units) which connects to terminals 1 and 2 of
the power connector on each module. A separate source of
21 vac power is used to power the PSIO-2 module and liquid
level sensor heaters. A separate 12.5 vdc power source is used
for the DSIO-EXV module through terminals 1 and 2 on the
power connector. The CPM modules are connected to 24 vac
power sources. Refer to Table 46 for control troubleshooting
information.
CONTROL MODULE BATTERY REPLACEMENT — The
PSIO-1 contains software that is stored in the RAM (Random
Access Memory). For this reason, a battery is required to main-
tain power and retain the software in the control module
memory.
A 3.6 volt AA lithium battery (part no. CEC0120803-01) is
required for all PSIO-1 modules. The nominal voltage is 3.6 to
3.7 volts, which is maintained throughout the life of the battery.
The power circuitry is designed so that the battery is always in
the circuit. The battery life will diminish faster if the module is
not powered. Battery life also depends on the steady state volt-
age of the unit and the ambient temperature of the module. Bat-
tery life expectancy of a 3.6 volt, AA lithium battery is about
4 years. Voltage drops rapidly at the end of battery life.
A part of a yearly maintenance schedule, check the voltage
level of the battery on each PSIO-1 module. If the battery reads
3.5 volts or less, the battery is approaching the end of its usage
life and should be replaced. The voltage should be measured
with the battery in place inside the module. With the control
voltage on, check the voltage by placing one test lead on each
pole of the battery.
As part of unit scheduled maintenance, replace the battery
every 4 years regardless of voltage reading.
Carrier Comfort Network (CCN) Interface —
The 30GX,HX 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 as shown in Fig. 25.
The positive pin of each system element communication con-
nector must be wired to the positive pins of the system ele-
ments on either side of it. This is also required for the negative
and signal ground pins of each system element. Wiring con-
nections for CCN should be made at the COMM1 plug on the
PSIO-1 module. Consult the CCN Contractor’s Manual for
further 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 appropriate
colors for different colored cables.)
3. Remove the 4-pin female plug from the PSIO-1 COMM1
plug and connect the red wire to terminal 1 of the plug, the
white wire to terminal 2, and the black wire to terminal 3.
4. Insert the plug back into the COMM1 plug.
Power must be applied to PSIO-1 module while replacing
battery or software loss will occur.
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.
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
CPM-2
CPM-1
HSIO-II
PSIO-2-J8
DSIO-EXV-J2
DSIO-HV-J2
PSIO-1-J8
Fig. 25 — Sensor Bus Wiring (Communications)
