ELECTRONIC CONTROLLING SECTION
DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)
OVERVIEW
The digital thermostat (controller) is a parametric controller for the complete management of air conditioners.
All settings are pre-programmed at the factory. Cooling/heating setpoint, cooling/heating differential and high/
low temperature setpoint are designed to be adjustable by the operator. All alarms are outputted through the
alarm relay. In addition, if Hoffman network card (Remote Access Control (RAC) Module) is used the parameters
that state above and alarms are accessible remotely through Ethernet connection utilizing SNMP, Modbus TCP,
EtherNet/IP, and Profinet protocol . A USB connection from the network card is also provided with accessibility
to the digital thermostat controller utilizing Modbus RTU and RS-845 serial bus. In addition, the USB connection
is also used to read the network information from the Hoffman network card and temperature setpoints and
alarm from the controller. Note that Hoffman network card (RAC module) is acting as a gateway to the digital
thermostat where temperature setpoints and alarm can be viewed and/or changed remotely.
NOTE: HOFFMAN NETWORK CARD (RAC MODULE) IS OPTIONAL ACCESSORY, THEREFORE,
SOME OF THE AIR CONDITIONERS SHIP WITHOUT THE NETWORK CARD BUT IT IS
UPGRADEABLE UPON REQUEST
ENERGIZING THE CONTROLLER
The digital controller is wired and programmed at the factory to operate when power is applied to the air
conditioner. In normal condition, the evap fan starts operating after the completion of the self-evaluation which
is less than 30 seconds and fan icon should be illuminated along with the inlet and outlet temperature data (if an
option outlet temperature sensor is installed).
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