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LogiTemp® Plus Description
LogiTemp Plus is an OEM version of the custom-designed microprocessor-based electronic controller for RSG to control
an electric expansion valve in response to evaporator superheat and return air temperature. The hardware and
input/output descriptions and connections of a LogiTemp Plus are shown in figure 2 on page 8.
• RSV or SER Terminals. Ke2Therm RSV or Sporlan SER-type electric expansion valves are currently used for all
applications. RSV has 500 nominal steps for the entire valve stroke and SER; has 1596 nominal steps for the entire
valve stroke. The default is the RSV valve.
• Pressure Transducer XDCR is mounted at the evaporator suction header to measure saturated suction pressure in
absolute value but displayed in gauge pressure in PSIG as “PrS”. The suction pressure is converted to saturation
temperature displayed as “tSt”. The difference between suction outlet temperature and evaporating temperature
is the true superheat displayed as “SUP”.
• Suction Outlet/Fan Cut-In Temperature Sensor Tsuc is mounted on the suction line about 6” to 10” away from the
evaporator to measure outlet temperature during the cooling cycle and to serve as an evaporator fan cut-in
temperature sensor. The sensor is at a 2 or 10 o’clock position on the suction line. The default value of the fan cut-
in temperature is pre-set at 35°F for freezers and 55°F for coolers. It is displayed as “tSC”.
• Room Temperature Sensor TAir is typically mounted with a plastic tie at the drain pan on the side of the evaporator
return air. It is located around the middle of the evaporator to allow even airflow across it. If necessary it can be
relocated to a spot with better representation of the cold room temperature. It is displayed as “rtP”
• Defrost Termination Temperature Sensor TCoil is mounted downstream of the distributor tube after the valve and
close enough to the evaporator coil to measure defrost termination temperature during defrost cycle. Figure 2 on
the next page shows the sensor locations of the evaporator and the controller. It is displayed as “tCL”.
• One 30 Amp NO NC 277 vac Relay is used for the compressor contractor or liquid line solenoid.
• One 30 Amp NO 277 vac relay is used to switch fans ON and OFF.
• One 30 Amp NO 277 vac Relay is used for a drain line heater.
• 0-10VDC Output is used to drive an SSR relay for triggering a buzzer in the control panel indicating a local alarm
inside the LogiTemp Plus controller.
• One Ethernet Port is used for connecting the edge manager (router) in the control panel to the LogiTemp Plus
controller. This is used in unison with the iPad for an interface for the user to control the system.
• Display Connection is connected to a 3-Digit remote display and keypad.
• RS485 (a+, B-, Shield) Terminals are used to communicate with the remote display as well as auxiliary boards for
extended applications.
• Power Input 120 to 208/240 vac.
• Green, Yellow and Red LED Status Indicators. The green LED will be on when the compressor relay is energized.
The green LED will blink when the air temperature is satisfied, but the compressor minimum off timer has not yet
timed out. The red LED indicates a critical alarm has occurred (Low-Pressure Alarm). The yellow LED indicates all
other alarms.
• Four Push Buttons on the remote display are used to display set points and status as well as to reset operational
parameters like room temperature, defrost mode, number of defrosts, etc. Their functions can also be performed
by using the TCP/IP interface.
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