5
CONTROL OPTIONS MODULE — The PSIO2 module
does not contain software. Through input and output channels
on the hardware, it supports the sensors used for:
• suction thermistors
• relative humidity
• outdoor-air cfm
• indoor-air quality (IAQ)
• smoke control
• supply air set point reset via external device
In addition, the PSIO2 supplies the outputs (4 to 20 mA sig-
nal) for humidifier and hydronic heating coil control, a discrete
output for timed clock control (for outdoor building or parking
lot lights), condenser fan staging (088-104 only), and a remote
alert light (088-104 only).
The PSIO2 options module is available as a factory-
installed option or as a field-installed accessory for sizes 034-
074 and is standard on sizes 078-104.
CB
— Circuit Breaker
CCB
— Control Circuit Breaker
CH
— Crankcase Heater
CLO
— Compressor Lockout
COMP
— Compressor
CR
— Control Relay
DPT
— Duct Pressure Transducer
DSIO
— Module Relay
DU
— Dummy Terminal
ECON
— Economizer
EQUIP — Equipment
FU
— Fuse
GND
— Ground Connection
HIR
— Heat Interlock Relay
*Standard on sizes 078-104.
Fig. 2 — Major Control Components in Control Box
HPS
— High-Pressure Switch
HR
— Heater Relay
IDC
— Induced-Draft Contactor
IFC
— Indoor-Fan Contactor
IFM
— Indoor-Fan Motor
IGV
— Inlet Guide Vanes
LPS
— Low-Pressure Switch
MM
— Motormaster® Control
MMC
— Motormaster Contactor
NEC
— National Electrical Code
OAT
— Outdoor-Air Thermistor
OFC
— Outdoor-Fan Contactor
OFM
— Outdoor-Fan Motor
PEDM — Power Exhaust Damper Motor
PL
— Plug Assembly
PRI
— Primary
PSIO
— Processor Module
RAT
— Return-Air Thermistor
RFM
— Return Fan Motor
SAT
— Supply-Air Thermistor
SCT
— Saturated Condensing Thermistor
SEC
— Secondary
SGT
— Suction Gas Thermistor
SPT
— Suction Pressure Transducer
TB
— Terminal Block
TRAN
— Transformer
U
— Unloader
LEGEND