Section 2 – SR-2 Hardware Description
GENERAL DESCRIPTION
The SR2 microprocessor controller is a self-
contained temperature control unit designed for
trailer applications. Model 30 units are powered by
a diesel engine and Model 50 units are powered by
either the diesel engine or an external electric
standby power source powering an electric motor.
The unit mounts on the nose of the trailer. Defrost is
by means of hot gas.
CAUTION
Dangerous three phase AC power is present
whenever the unit is operating in Electric mode
and whenever the unit is connected to external
standby power. Voltages of this magnitude can
be lethal. Exercise extreme caution when
working on the unit.
CONTROL SYSTEM
The SR2 Microprocessor Control System consists of
the following main components:
• Microprocessor On/Off Switch
• HMI (Human Machine Interface) Control Panel
• Microprocessor
• Interface Board
• Unit Sensors
• Refrigeration Control Components
• Engine Control Components
• Communication Ports
• Optional Electric Standby
CONTROL COMPONENTS
The base of the control system is the micro-
processor. The interface board is mounted on the
microprocessor and is connected to it by means of
connectors J1 and J2. When connected, the
microprocessor and interface board form a one-
piece assembly. The unit is controlled by means of
the HMI Control Panel.
SB SERIES CONTROLS
The control panel shown below is used on SB-110,
SB-210 and SB-310 units.
SmartReefer2
OFF
ON
MENU
35
°F
35
CYCLE SENTRY
SET SENSORSGAUGES
POINT
.8
CARGO WATCH SERVICE WATCH
THERMO KING
2-4
31 January 2005
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