Abstract:
A programmable system for controlling the refrigeration of a transportable container is provided. The system is programmed by insertion of a card into the control system so as cause a control program to be transferred from the card to a memory within the control system.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the control of a refrigerating system used in the transport of refrigerated products. More particularly , this invention relates to the method and apparatus for loading a control program into a microprocessor based control system for controlling the aforementioned refrigerating system. 
     Systems for controlling the refrigeration of perishable goods in transit have previously included programmed microprocessors. These microprocessor based control systems have usually included control programs which define the control functions for controlling the refrigerating system. These control functions include by way of example compressor control algorithms and defrost control algorithms. The above control functions are implemented in accordance with a control program after the program has been selectively read into the microprocessor. 
     The control program usually resides on a dedicated read only memory and is typically booted or read into the microprocessor at such times as the control system is activated. In order to change the control program in the aforementioned microprocessor based control system, it is usually necessary to disassemble a portion of the control system housing and thereafter physically remove the read only memory. These memories are then usually replaced with a newly programmed read only memory containing the new control program for the microprocessor based control system. 
     What is needed is a microprocessor based control system for a refrigerated transport system wherein the control program may be provided to the system in a more cost effective and less complicated manner. 
     SUMMARY OF THE INVENTION 
     Accordingly it is an object of the present invention to provide a control system wherein the control program is provided in a manner that does not require inserting or replacing a programmed read only memory within the control system. 
     As a further object of the present invention, a control program is provided to the system in a manner which does not require physically disassembling the control system. 
     The above and other objects of the present invention are achieved by providing a control system with a versatile card reader which is capable of reading a control program residing on a card. In accordance with the preferred embodiment, the card is inserted into the card reader in such a manner as to activate a microprocessor which proceeds to read the control program residing on the card. The thus read program is transferred to a target memory associated with the microprocessor. Upon removal of the card, the microprocessor will access the thus transferred control program from the target memory and begin to execute the control functions for controlling the refrigerating system. In the event that the control program is to be revised, a card containing a newly revised program is merely inserted into the card reader for subsequent transfer to the target memory associated with the microprocessor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the present invention will be apparent from the following detailed description in conjunction with the accompanying drawings, in which: 
     FIG. 1 illustrates a refrigerated transport system having a container vessel and refrigerating system attached thereto; 
     FIG. 2 illustrates certain controls available to a person wishing to program a control system associated with the refrigerating system of FIG. 1; 
     FIG. 3 illustrates a card reading system in association with a microprocessor which facilitates the transfer of a control program for the control system; and 
     FIG. 4 is a flow chart depicting a copy program present on the card that is to be read by the card reading system of FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a system which may be transported by land or sea is seen to include a transport container 6 and a refrigerating system 8 attached thereto. A control system associated with the refrigerating system is accessed by opening a hinged door 10. 
     Referring now to FIG. 2, the control system behind the hinged door 10 is seen to include a display 12 and a keypad entry 14. The control system furthermore includes a housing 16 having a slot 18 therein. The slot 18 is preferably covered by a tape 20 which normally seals the slot 20 except when the control system is to receive a control program. In accordance with the preferred embodiment, the tape 20 is removed when it is desired to insert a card containing a control program to be loaded into the control system. Upon loading of the control program into the control system, a new tape 20 is subsequently applied to the slot 18. The new tape 20 will contain information identifying the control program that has been thus loaded into the control system. This information would for instance include the control program revision number. 
     Referring now to FIG. 3, a card 22 having a plurality of electrical contacts 24 is inserted into a card reading device 26 that is located behind the slot 18. The electrical contacts 24 are caused to register with electrical sensors within the card reader 26. One of the electrical contacts on the card 22 registers with an electrical sensor associated with a line 28. This particular contact is preferably interconnected with another contact on the card 22 that receives the power supply voltage from the card reading device 26. This interconnection causes a logically high signal to occur on the line 28 when the card is completely inserted. The logically high signal on the line 28 triggers a pulse generator 30 to generate a pulse 32 that is applied to a microprocessor 34. In this regard, the pulse generator preferably generates the pulse 32 anytime there is a change in signal state from low to high or high to low at its input. 
     The microprocessor 34 in response to the pulse 32 generates a preset address over an address bus 36 to a memory system 38 and to the card reader 26. The address that is preset in the microprocessor identifies the first addressable storage location for the control program when it resides in the memory system 38. It identifies the address of a first location of a copy program in the card reader 26. Referring again to the line 28, the logically high signal from the card reader 26 indicating that a card 22 is in place will also be applied via a line 40 to selection logic 42. The selection logic 42 also receives a signal from the microprocessor 34 via a line 44 which is preferably the highest ordered address bit from the microprocessor 34. 
     The microprocessor 34 in combination with the selection logic 42 addresses storage locations in either a lower ordered addressable memory bank 46 or a higher ordered addressable memory bank 48 within the memory system 38 or it addresses storage locations in the card reader 26. The particular storage locations which are addressed will be a function of the bi-level signal present on the line 44 as well as the bi-level signal present on the line 40. The actual selective enabling of the lower ordered addressable memory bank 46 is via a line 50 whereas the selective enabling of the higher ordered addressable memory bank 48 will be via a line 52. The enabling of the card reader 26 will be via a line 54. The signal levels present on the lines 50, 52 and 54 in response to the signal levels present on the lines 40 and 44 are dictated by the selection logic 42 and can be summarized as follows: 
     
         ______________________________________LINE 40   LINE 44  LINE 50    LINE 52                                LINE 54______________________________________0         0        1          0      00         1        0          1      01         0        0          0      11         1        1          0      0______________________________________ 
    
     It is to be appreciated from the above table that a binary zero is equivalent to a logically low level signal on a given line and a binary one is equivalent to a logically high level signal on a given line. It is furthermore to be appreciated that the above table is easily implemented within the selection logic 42 in accordance with traditional, well understood binary logic principals. 
     Referring now to FIG. 3, when the line 40 is logically high indicating that a card is in place within the card reader 26, the selection logic 42 will be operative to select the lower ordered addressable memory bank 50 in response to a logically high signal present on the line 44. This is accomplished by the selection logic 42 generating a logically high level signal on the line 50 and a logically low level signal on the line 52 which enables only the lower ordered memory bank 46 within the memory system 38. On the other hand, when the microprocessor 34 wishes to access the storage locations on the card 22, it will produce a logically low level signal on the line 44 which will in turn cause the selection logic to produce only a logically high signal on the line 54. The logically high signal on the line 54 will enable the card reader 26 to respond to addressing on the address bus 36 and provide control program information to the microprocessor 34 via a data bus 56. 
     In summary, when the card reader 26 is indicating that a card is in place, the lower ordered memory bank 46 will be accessed by the microprocessor 34 when the address line 44 is logically high and the card reader 26 will be accessed when the address line 44 is logically low. In either case, the microprocessor will be operative to receive information from the card reader 26 and transmit information to the lower ordered memory bank 46 via the data bus 56. 
     Referring now to FIG. 4, a copy program resident on the card 22 is illustrated. It is to be understood that the copy program will begin at an addressable storage location on the card 22 which is the initial address generated by the microprocessor 34 over the address bus 36 immediately following generation of a reset pulse 32 by the pulse generator 30. 
     The copy program begins with an introduction message that is to be displayed on the display 12 pursuant to a step 58. This introduction message will indicate to an operator that the card has been successfully inserted into the slot 20 and that the control system is now awaiting authorization to proceed forward with loading of the control program into the control system. The copy program will accordingly in a step 60 await a keyboard entry from the operator who has read the introduction message. When a keyboard entry is made, the copy program will proceed to generate a copy message on the display 12 in a step 62. The copy program thereafter proceeds in a step 64 to instruct the microprocessor to copy the control program into certain addressable storage locations. These addressable storage locations will begin with the preset address normally generated by the microprocessor upon being reset except that the highest ordered address bit will be a binary one instead of a binary zero. This highest ordered address bit will cause the microprocessor to generate a logically high signal on the line 44. The selection logic 42 will in turn generate a logically high level signal on the line 50 so as to enable the lower ordered memory bank 46 to receive the control program beginning at the preset address. 
     When the control program is completely copied, the copy program exits in a step 66 to a step 68 and causes the display 12 to display a message indicating &#34;finished&#34;. 
     The card may be removed when the operator observes the finished message on the display 12. It is preferable at this point in time that the slot 18 be resealed with a tape 20 so as protect the electronic components within the housing 16. The tape also serves the purpose of identifying the thus loaded control program. Referring again to FIG. 3, when the card 22 is removed from the card reader 26, the signal on the line 28 will drop logically low indicating that a card is no longer in place. This will cause the pulse generator 30 to generate a second reset pulse 32 to the microprocessor 34. The thus reset microprocessor 34 will again generate the same address that has been preset in the microprocessor. This will include the bi-level signal on the line 44 being logically low. The selection logic 42 will be operative to select the lower ordered memory bank 46 in response to the card sense line 40 now being logically low. In this manner, the control program previously stored in the lower ordered memory bank 50 will now be accessed by the microprocessor 34 and thereafter implemented. It is to be understood that implementation of the control program may require use of the higher memory bank which is freely available during such time as the control program is being read from the lower memory bank. 
     It is to be appreciated that the microprocessor 34 when implementing the thus stored control program will interface with an overall refrigerating control system 70 so as to appropriately control the cooling of the transport container 6. This will include such functions as have been heretofore described. In the event that the control is to be revised or otherwise changed, a new control program can be loaded into the system via a card 22. In this manner, the control functions for the control system 70 can be changed, enhanced or otherwise revised without disassembling or otherwise physically disturbing any internal electronic circuits. 
     While the invention has been described with respect to a preferred embodiment, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the scope of the invention. In this regard, while the invention has been disclosed relative to the cooling of a transportable container, it could also be used in a control system that cools or heats any spatial volume. It is therefore intended that the scope of the present invention be limited only by the scope of the following claims.