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: 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: 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 controlling a refrigeration system by determining an average air temperature by sensing and averaging evaporator return and discharge air temperatures, and developing an average error by using the average air temperature and a selected set point temperature. The average air temperature is then used to calculate a proportional error and an integral error, and the discharge air temperature is used to calculate a floor error. The proportional error, integral error and floor error are weighted by predetermined gain factors and then summed to provide an error signal which is used to modulate the capacity of the refrigeration system, with the control mode depending upon the location of the error signal relative to set point.

Abstract: A power line carrier communication system for monitoring refrigerated containers which includes a master monitoring unit and a first power line interface which interchange messages in a first format. The first power line interface translates the first format to a second format suitable for power line environment, and messages in the second format are applied to a power line. Remote monitoring units receive the messages from the power line, and they return messages to the power line containing status data relative to refrigerated containers. The second format includes a message starting preamble having a duration and logic level which is not duplicated by normal operation of the apparatus, enhancing the probability of proper message synchronization and reception over noisy power line environments.

Abstract: A transport refrigeration unit is provided with a control box 16 arrangement in which a hard-wired electrically passive assembly of receptacles 23, 24 and electrical terminal strips 25-27, and interconnecting wires 28-30 at the rear wall 18 of the box is arranged to be electrically connected to the interface module 33 through the plugs 39, 40 being received in the passive assembly receptacles, the interface module having both high voltage and low control voltage elements 41-48, the interface module also having a forwardly facing low voltage receptacle 49 which receives the front module 33 plugs 60 at the rear of the front module, the front module having only low control voltage elements 61-63 and a door 73 for the box provided with control switches 75 connected through wiring 76 and plug 78 to receptacle 79 so that all of the electrical elements of the front module and the door are of low control voltage.