Abstract: A method of determining the condition of a battery which backs up a real-time clock (RTC) when a main power supply fails or is disconnected, in a system which includes a controller having a volatile random access memory (VRAM) and a non-volatile random access memory (NVRAM). The method includes the steps of periodically storing the time value of the RTC in NVRAM, and periodically writing a predetermined data pattern in VRAM, while the main power supply adequately powers the real time clock. The method then includes the steps of detecting a power-down condition of the main power supply, and terminating the recording and writing steps when the detecting step detects power-down. Return of main power, or power-up, is then detected, with the data pattern stored in VRAM then being compared with the predetermined data pattern.

Abstract: A method of adding asynchronous logging of data relative to events into a time based data logger which stores operator initiated headers in a data array, as well as synchronously storing data relative to variables of a transport refrigeration unit at predetermined constant time intervals. The operator associated headers include a preamble having a predetermined number of data bytes which include a header designator and a digital code which identifies the specific type of header being entered. An event header is provided having a preamble which includes the same number of data bytes as the preamble of the operator associated headers, for each type of event to be asynchronously stored in the data array. The header designator associated with the operator associated headers is inserted into the preamble of each of the event headers. A digital code is provided which identifies each event header, and the digital code is inserted into the preamble of each of the event headers.

Abstract: A method of securely controlling direct memory access (DMA) in a microprocessor controlled system having a CPU on a CPU board which has an address/data bus connector for selectively connecting an expansion board to the CPU board, and a random access memory (RAM) on the CPU board having a specific address range which is accessible by a DMA device on the expansion board when the CPU board relinquishes control of the address/data bus to the DMA device in response to a bus access request.

Abstract: Methods and apparatus for converting a refrigeration unit having a manually controlled thermostat to remote operation via a data logger, without replacing the manually controlled thermostat. A set point temperature selector associated with the thermostat is fixed at a predetermined value, and a resistance temperature detector (RTD), which is normally connected to a temperature input of the thermostat, is disconnected. A set point temperature for a space conditioned by the refrigeration unit is selected via the data logger. The data logger monitors the temperature of the conditioned space, compares the temperature of the conditioned space with the set point temperature selected via the data logger, and determines an operating mode for the refrigeration unit which will cause the temperature of the conditioned space to be maintained in a predetermined range relative to the set point temperature selected via the data logger.

Abstract: A method of logging data relative to the operation of a transport refrigeration unit, during each trip of the transport refrigeration unit, with the transport refrigeration unit including control means and non-volatile memory means. The method includes the steps of monitoring a plurality of predetermined variables of the transport refrigeration unit to provide data, and selecting those variables of the plurality of monitored variables whose data is to be logged in the memory means during a trip of the transport refrigeration unit. The method further includes the steps of dividing the non-volatile memory means into at least first and second data segments for storing data from the selected variables, storing an address pointer in the first data segment which points to an address in the second data segment, for each trip of the transport refrigeration unit, and storing data from the selected variables in the second data segment, during each trip of the transport refrigeration unit.

Abstract: A method of interchangeably using memory devices constructed from different memory technologies, and/or having different storage capacities, in a predetermined socket of an electrical circuit. The method includes the steps of determining which technology types of memory devices, and storage capacities thereof, are to be interchangeably inserted in the predetermined socket, determining which pin positions of the determined memory devices have like functions, and determining which pin positions have different functions. The method further includes the steps of connecting the socket in the electric circuit such that a predetermined placement position of each determined memory device in the socket will serve the pin positions determined to have like functions.

Abstract: A method of communication in a refrigeration system, between communication nodes connected to a serial data bus using Controller Area Network protocol (CAN) having a message frame format which includes a data field. The method includes converting a byte of the data field of each message frame to a permanent data descriptor expansion byte (DEB). In at least the first frame of a message a specific bit of the DEB is set to a first logic level to indicate a control frame, and information descriptive of the whole message is loaded into the remaining bits of the DEB, and data field. In each remaining frame of a message following a control frame, or control frames, the specific bit is set to a second logic level, to indicate a data frame. A block of data is loaded into the data field of each data frame, and index information specific to the associated block of data is loaded into the remaining bits of the DEB.

Abstract: The invention relates to methods of defrosting an evaporator coil of a transport refrigeration unit which includes microprocessor based electrical control. The electrical control maintains the temperature of a conditioned space at a predetermined set point temperature via hot gas heating and cooling cycles. The evaporator coil is defrosted to remove frost and ice by closing a damper to the served space and initiating a heating cycle. At the termination of defrost, a cooling cycle is initiated, but the damper is maintained in a closed position for a predetermined period of time to remove heat built up during the defrost process. The invention also detects damper malfunctions, including failure to close prior to defrost, and failure to open after defrost. The invention also evaluates manual and timed requests for a defrost operation, overriding the requests in response to predetermined conditions.

Abstract: A method of operating a transport refrigeration system having a refrigerant compressor driven by a prime mover. Electrical control maintains the temperature of a load in a conditioned space close to a desired set point via heating, cooling and null cycles, with the prime mover being started and stopped, as required, in response to the difference between the temperature of the conditioned space and a selected set point temperature, i.e., temperature error. Restarting of the prime mover is dynamically controlled by controlling the magnitude of the restart temperature error in response to the difference between the temperature of the conditioned space and ambient temperature.

Abstract: A transport refrigeration unit, and methods and apparatus for monitoring the operation thereof, with the unit conditioning a load to a selected set point temperature via commanded cooling and heating cycles. A thermostat provides a digital signal as a function of the load temperature and the selected set point temperature, with each toggling of the least significant bit (LSB) thereof indicating a predetermined change in load temperature. A timer initiates a predetermined timing period with each toggling of the LSB, with the timing period being a dynamic function of the selected set point temperature. Expiration of the timing period before the next bit toggle initiates an alarm signal indicating the rate-of-change of load temperature is not within an acceptable limit for the selected set point temperature. A comparison of successive digital signals also results in an alarm signal when the direction of temperature change is not consistent with the commanded operating cycle.

Abstract: A method of operating a transport refrigeration system having a compressor driven by a prime mover at a selected one of high and low speeds, an evaporator, and an evaporator blower driven by the prime mover. Refrigeration control provides an error value which controls the temperature of a load space to a predetermined set point via heating and cooling modes. The method includes the steps of driving the compressor at high speed during pull down, and injecting hot gas into the evaporator when the error is reduced to a predetermined value. The prime mover is maintained at high speed, to keep evaporator air flow at a high rate, continuing a relatively rapid temperature pull-down across the entire load space. The speed of the prime mover is reduced to low speed when the error is further reduced to a second value, which also initiates suction line modulation while maintaining hot gas injection.

Abstract: A method of operating a transport refrigeration unit having electrical control which includes a display, including the steps of detecting the occurrence of predetermined events in the transport refrigeration unit, and classifying at least certain of them into first, second and third categories of fault conditions, and into a fourth category related to maintenance associated events. When a first category fault occurs, the unit is shut down, a visual alarm is flashed, and the nature of the fault is immediately identified. When a second category fault occurs, a visual alarm is steadily energized, and the nature of the fault if immediately identified. When third category faults and fourth category events occur, they are stored and periodically displayed, with the display respectively identifying the nature of the fault and the type of maintenance event.