5370597-JIM-D-1019
54
Johnson Controls Ducted Systems
FAULT
Red hard lockout, networking error and firmware
error indicator
1/2 second on/off flashing indicates one or more alarm is
currently active, 1/10th second on/off flashing indicates a
networking error (polarity, addressing, etc.) or a firmware error
(likely correctable with re-loading from USB flash drive)
SA BUS
Green UCB SA bus communication transmission
indicator
Lit/flickering indicates UCB SA bus communication is currently
active, off indicates the UCB is awaiting SA bus communication
Terminal Space temperature sensor connections at center on upper edge of UCB
ST
Space Temperature sensor input from 10KΩ @
77°F, Type III negative temperature coefficient
thermistor
Positive of VDC circuit (3.625 VDC reading to COM with open
circuit), effective if “Thermo- stat-only Control” parameter is set
OFF, space sensor override momentary shorts ST to COM to
initiate/terminate temporary occupancy
COM
Common for ST and SSO inputs
Negative of VDC circuit for ST and SSO inputs
SSO
Space Sensor Offset input from 0 to 20KΩ
potentiometer
Positive of VDC circuit (3.625 VDC reading to COM with open
circuit), 10KΩ/2.5 VDC is 0°F offset, 0Ω/0 VDC is maximum
above offset and 20KΩ/3.4 VDC is maximum below offset from
active space temperature setpoint
Pin Temperature sensor connections at right on upper edge of UCB
SAT+
Supply Air Temperature sensor input from 10KΩ
@ 77
°
F, Type III negative temperature coefficient
thermistor
Input required for operation; 3.625 VDC reading SAT+ to SAT
–
with open circuit. Used in heat/cool staging cutouts, free cooling
operation, demand ventilation operation, comfort ventilation
operation, economizer loading operation, VAV cooling
operation, hydronic heat operation.
RAT+
Return Air Temperature sensor input from 10KΩ
@ 77°F, Type III negative temperature coefficient
thermistor
Input required for operation; 3.625 VDC reading RAT+ to RAT
–
with open circuit. Used in return air enthalpy calculation.
Substitutes for space temperature if no other space
temperature input is present.
OAT+
Outside Air Temperature sensor input from 10KΩ
@ 77°F, Type III negative temperature coefficient
thermistor
Input required for operation but may be a communicated value;
3.625 VDC reading OAT+ to OAT
–
with open circuit. Used in
heat/cool cutouts, low ambient cooling determination, dry bulb
free cooling changeover, outside air enthalpy calculation,
economizer loading operation, heat pump demand defrost
calculation.
CC1+
#1 refrigerant circuit Condenser Coil temperature
sensor input from 10KΩ @ 77°F, Type III negative
temperature coefficient thermistor
Input required for heat pump units, not required for A/C units;
3.625 VDC reading CC1+ to CC1
–
with open circuit. Used in
heat pump demand defrost calculation.
EC1+
#1 refrigerant circuit Evaporator Coil temperature
sensor input from 10KΩ @ 77°F, Type III negative
temperature coefficient thermistor
Input required for operation; 3.625 VDC reading EC1+ to EC1
–
with open circuit. Used in suction line temperature safety.
CC2+
#2 refrigerant circuit Condenser Coil temperature
sensor input from 10KΩ @ 77°F, Type III negative
temperature coefficient thermistor
Input required for 2-compressor heat pump units, not required
for 2-compressor A/C units, not active for 1-compressor units;
3.625 VDC reading CC2+ to CC2
–
with open circuit. Used in
heat pump demand defrost calculation.
EC2+
#2 refrigerant circuit Evaporator Coil temperature
sensor input from 10KΩ @ 77°F, Type III negative
temperature coefficient thermistor
Input required for operation of 2-compressor units, not active for
1-compressor units; 3.625 VDC reading EC2+ to EC2
–
with
open circuit. Used in suction line temperature safety.
Pinned connections on right edge of UCB
RAH+
Return Air Humidity input from 0-10 VDC @ 0-
100% RH sensor
Input required for reheat units, optional in all other units, may be
a communicated value. Used in return air enthalpy calculation,
temperature/humidity setpoint reset, reheat operation.
DCT PRS+
Supply Duct Pressure input from 0-5 VDC @ 0-5”
w.c. sensor
Input required for variable air volume units. Used in VAV indoor
blower operation.
DFS (upper pin)
24 VAC hot return from Dirty Filter Switch
Optional input; switch closure for greater than 15 seconds
during indoor blower operation initiates a notification alarm
Table 29: Smart Equipment™ UCB Details (Continued)
Description
Function & Comments
