Abstract:
A modular electronic device has a cabinet frame, a plurality of push-in modules with module frames retained in the cabinet frame side-by-side, and printed circuit boards mounted in the module frames, and electronic components carried by said printed circuit boards. Each of these modules has autonomous data transmitting connections for communicating directly with each of the other ones of the modules.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a modular electronic device. More specifically, the electronic device has a cabinet frame. The modules have module frames. Printed circuit boards are held in the module frames. Electronic components are mounted on the printed circuit boards. The modules with the module frames are pushed into the cabinet frame side-by-side and can be pulled out individually. 
     Furthermore the invention relates to a method of communication between such modules. 
     In avionics, different avionic functions are installed in autonomous units. When a failure occurs, the whole unit will be exchanged. Quite often, this unit consists of a housing in which the individual avionic functions are installed. The tendency, in avionics, is, however, using modular systems. This offers the advantage that, in the case of a failure of an avionic function, it will not be necessary to exchange the whole unit, but only the failing module needs to be exchanged. As a rule, these modules are printed circuit boards cannying electronic components. The printed circuit boards are mounted in a module frame, which can be pushed into a cabinet frame. 
     Information has to be exchanged between the individual modules. In the prior art, the communication is established through a data bus extending in the back wall of the cabinet frame. When the module are pushed into the cabinet frame, they are interconnected through appropriate plug-and-socket connectors connecting each module with the data bus. 
     The priciple of data busses is well known. A classical “multi-transmitter /multi-receiver”—data bus is a multi-wire line for data transfer between a plurality of functional units. With such a bus structure, basically one transmission line is required, all units being connected with this transmission line. The communication of all units is carried out through through this transmission line. This is, on one hand, a simple structure. However this simple structure, on the other hand, requires a complex administration. As, in principle, all connected units are able to transmit and to receive messages, care has to be taken to prevent a plurality of different units from transmitting data simultaneously, and to ensure that only those units for which the instantaneously transmitted data are intended are switched on reception. Therefore, the administration of the bus is usually handled by a particular bus controller. 
     The ARINC-standard “ARINC 659” describes a so-called “backplane bus”. The backplane bus is a bus system which is arranged in the back wall or backplane of a push-in cabinet. In this standard. The bus system is a so-called “multiplex-bus” German patent 41 32 994 describes a modular push-in system comprising modules with printed circuit boards, which carry electric components. 
     Published European patent application EP 0,824,302 A1 describes a modular electronic device with printed circuit boards carrying electric components. The printed circuit boards are mounted in module frames of push-in modules. The push-in modules, in turn, are retractably retained in a cabinet frame. The push-in modules are electrically connected with a backplane component. 
     Published German patent application 34 17 451 describes a right-parallelepipedal push-in system for an electronic device into which printed circuit board inserts or the like can be pushed in. 
     The prior art module communication of push-in insert cabinets suffers from the disadvantage that the safety of the data transfer from one module to another cannot be ensured without limitations. Avoiding collisions requires expensive organisation of the data flux. At the same time, however, this increases the error proneness of the data flux, as the communication processes between the individual modules are not mutually independent. 
     It has been found disadvantageous with prior art devices that conventional bus structures do not permit easy recognition, when the communication of a module is no longer operative. 
     DISCLOSURE OF THE INVENTION 
     It is an object of the invention to provide a modular electronic device which avoids the disadvantages of the prior art. 
     It is a further object of the invention to ensure that communication within the electronic device is collision-free, determined in time and, during data transmission, independent of other devices or internal functions. 
     To this end a modular electronic device comprising a cabinet frame, a plurality of push-in modules with module frames retained in said cabinet frame side-by-side, and printed circuit boards mounted in said module frames, and electronic components carried by said printed circuit boards is provided, wherein each of said modules has autonomous data transmitting means for communicating directly with each of the other ones of said modules. 
     In a method of communication between modules of a modular electronic device comprising a cabinet frame, a plurality of push-in modules with module frames retained in said cabinet frame, and printed circuit boards mounted in said module frames, and electronic components carried by said printed circuit boards, said modules are directly interconnected for data exchange. 
     Thanks to the direct transmission of the data from one module to another, freedom of collision during data transfer is achieved. The control of the communication between the modules is independent of the processor units of the modules. When direct communication of the modules with each other is used, it is considerably more easy than with the prior art to add further modules to a already communicating module system. The communication of already communicating modules is not disturbed by added modules. 
     Preferably, said data transmitting means of each of said modules comprise a data transmitting controller. This controller controls the data transmission to the other modules. Data memories provided in the respective modules and connected with the data transmitting means permits temporary storage of data. 
     A further advantageous modification is that the data transmitting means have both a transmitting device for data transmission and a corresponding receiver device. It may, however, also be sufficient if either a receiver device only is provided in the data transmission means or a transmitting device. 
     By using a time-controlled communication protocol, the data transmission becomes transparent and safer. 
     Interfaces at the modules establish, in the cabinet frame, the communication with the remaining modules. 
     Preferably, the electronic devices of the invention are used in aircraft. Then, the cabinet frame of the electronic device may be an integral part of the aircraft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration of the cabinet frame with a multiplex data bus and removable modules according to the prior art. 
     FIG. 2 is a schematic illustration of an electronic device of the invention with direct module communication. 
     FIG. 2 a  is a schematic illustration of the direct module communication of the invention with a transmitting device and a plurality of receiver devices. 
     FIG. 2 b  is a schematic illustration of the direct module communication of the invention, wherein one receiver device is associated with each transmitting device. 
     FIG. 2 c  is a schematic illustration of the direct module communication of the invention in a combination of the structures of FIGS. 2 a  and  2   b.    
     FIG. 3 is a schematic illustration of the module structure in the area which is relevant for the direct module communication. 
     FIG. 4 illustrates the principle of the transmission protocol. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In order to facilitate the description of the invention, the operation of a prior art electronic device of the present type is described with reference to FIG.  1 . Referring to FIG. 1, numeral  10  designates a cabinet frame. In its rear wall  12 , the cabinet frame has a single multiplex-data bus  14 . In the simplest case, this multiplex-data bus  14  consists of a cable. Exchangeable electronic modules  16 ,  18 ,  20 ,  22  are pushed into the cabinet frame  10 . To this end, the modules  16 ,  18 ,  20 ,  22  each have a module frame  17 ,  19 ,  21 ,  23 , which can be pushed into the cabinet frame  10 , until they make contact with a power supply and the multiplex-data bus  14 . The number of modules  16 ,  18 ,  20 ,  22  are dependent on the accommodation capacity of the cabinet frame. The individual modules  16 ,  18 ,  20 ,  22  are interconnected through multiplex-data bus  14 . This is illustrated by arrows  14   a ,  14   b ,  14   c ,  14   d . The data flux between the modules  16 ,  18 ,  20 ,  22  of the cabinet frame  10  is controlled either by a bus controller or by a corresponding transmission protocol of each individual module in multiplex operation. As a whole, the cabinet frame  10  with the modules  16 ,  18 ,  20 ,  22  and the data bus  14  form an operative electronic device  24 . 
     FIG. 2 shows an electronic device  24  similar to FIG.  1 . In this electronic device, however, no data bus is used. The exchangeable electronic modules  30 ,  32 ,  34 ,  36  are pushed or inserted into the cabinet frame  10 . To this end, the modules  30 ,  32 ,  34 ,  36  have module frames  31 ,  33 ,  35 ,  37  which can be pushed or inserted into the cabinet frame, until they make contact with a power supply. The dots  28  indicate that any number of modules (not shown) may be used. The number of modules  30 ,  32 ,  34 ,  36  depends on the accommodation capacity of the cabinet frame  10 . Here, according to the invention, each module  30 ,  32 ,  34 ,  36  is directly connected with the other modules  30 ,  32 ,  34 ,  36  through direct connections  38 ,  40 ,  42 ,  44 ,  48 ,  50 . 
     Arrows  38   a ,  40   a ,  42   a ,  46   a ,  48   a ,  50   a ,  38   b ,  40   b ,  42   b ,  46   b ,  48   b ,  50   b  indicate that the data flux through the direct connections may be in two directions. In the present embodiment, this is achieved, with each pair of modules, by two separate unidirectional connections. At least one data bus is used for each direction of the data flux and each receiver. If required, also a unidirectional connection can be used, such that the data flux passes in one direction only through one separate connection. The connections for the data transmitting may be adapted both for serial or parallel transmission. 
     Dashed lines  52  indicate further direct connections with modules not shown for clarity. Each of the modules has its own data transmission controller (DÜK)  54 ,  56 ,  58 ,  60 . The data transmission controller (DÜK)  54 ,  56 ,  58 ,  60  have specific components or, with integrated circuits, specific functions for data transmission. Furthermore, a data memory (RAM)  62 ,  64 ,  66 ,  68  and a processor unit (CPU)  70 ,  72 ,  74  and  76  are provided in each of the modules  30 ,  32 ,  34   36 , respectively. The data transmission controller (DÜK)  54 ,  56 ,  58 ,  60  control the communication with the respective other modules. As a whole, the cabinet frame  10  with the modules  30 ,  32 ,  34  and  36  form an operative electronic device. 
     FIGS. 2 a  to  2   c  are to show various modes of direct communication between modules of a device  24  of the invention. In FIGS. 2 a  to  2   c , the removable modules  30 ,  32 ,  34  and  36  are shown as blocks. Dots  28  indicate that any number of modules could be used. The number of modules is, however, dependent only on the accommodation capacity of the cabinet frame. Referring to the embodiments of FIGS. 2 a  to  2   c , the transfer of data from a first module  30  to the other modules  32 ,  34 ,  36  is to be described: 
     In the embodiment of FIG. 2 a , only one transmitting device  54   b  of the first module  30  is shown. The transmitting device  54   b  may be an integral part of the data transmission controller or may be a separate component. By dividing the connection cable, the transmitted data of the first module  30  are sent to receivers  56   a ,  58   a  and  60   a  of the modules  32 ,  34 ,  36 , respectively, on direct paths through the connections  38 ,  48  and  50 . The receiver devices  56   a ,  58   a  and  60   a  are also either part of the data transmission controller or are separate components. 
     In the embodiment of FIG. 2 b , an own transmitting device  54   c ,  54   d ,  54   e  of the first module  30  is shown for each direct connection  38 ,  48 ,  50 , respectively. The transmitting devices  54   c ,  54   d ,  54   e  may be integral parts of the data transmission controller or may be separate components. In this embodiment, dividing the connection cable is not necessary, as a separate transmitting device is provided for each receiver device. The data to be transmitted from the first module  30  are sent on direct paths through connections  38 ,  48  and  50  to receiver devices  56   b ,  58   b  and  60   b , respectively, of the other modules  32 ,  34 ,  36 , respectively, where they are, eventually, stored, for further processing, in a data memory. The receiver devices  56   a ,  58   a  and  60   a  are either part of the data transmission controller  54  or are separate components. 
     The embodiment of FIG. 2 c  combines the two modes of direct connection shown in FIG. 2 a  and FIG. 2 b . Referring to FIG. 2 c , both a transmitting device  54   f  with division of the transmitting cable and a transmitting device  54   g  without division of the connecting cable are provided. The transmitting devices  54   f  and  54   g  may be integral parts of the data transmission controller  54  or may be separate components. The transmitted data of the first module are sent to receiver devices  56   b ,  56   b  and  60   b  of the other modules  32 ,  34 ,  36 , respectively, on direct paths through the connections  38 ,  48  and  50 , where they eventually are stored, for further processing, in a data memory. The receiver devices  56   a ,  58   a  and  60   a  may be either integral parts of the data transmission controller or may be separate components. 
     The modes of direct data transmission, as illustrated in FIGS. 2 a  to  2   c , prevent the data fluxes from colliding in any way, as these fluxes pass always on direct paths from the transmitting device to the receiving device. 
     FIG. 3 illustrates, in principle, the module construction of a module  30 , as required to permit direct communication with other modules. The module  30  contains a functional unit  90  which performs the module function proper, and a data transmitting unit  92  for transmitting data. In this illustration, the functional unit  90  is shown separated from the data transmitting unit  92  by a line  94 . The functional unit  90  comprises a processor unit (CPU)  70  and a memory  96 . The processor unit  70  is connected with the memory  96 . Arrow  97  indicates the access to the memory  96 . The data memory  62  for the data transmitting may be a data memory separated from the functional unit  90 , but may also be integrated in the memory  96  of the functional unit  90  as a memory area, as shown in this embodiment. Therefore, the memory  96  of the functional unit  90  reaches, as a dashed partial block  98 , also into the data transmitting unit. 
     The data transmission controller  54  is connected with this data memory  62 . The data exchange is symbolized by arrow  100 . Data to be transmitted are stored in the data memory  62  either directly by the processor unit  70  or indirectly through the data transmission controller  54 , depending on whether the processor unit has direct access to the data memory  62  or not. Furthermore, the data transmission controller  54  comprises a receiver device  54   a  and a transmitting device  54   b . The receiver device  54   a  and the transmitting device  54   b  serve to receive data from other modules or to transmit data to other modules, respectively. Arrows  102  and  104  indicate the receiving and the transmitting, respectively. As required, the data may be transferred between the modules either serially or in parallel. All data transmitting functions and the elements therefor are, as far as possible, separated from the remaining module function of the respective module. 
     FIG. 4 illustrates the principle of a transmission protocol required for the direct communication. This is a time-controlled, not interrupt-controlled transmission protocol. The transmission protocol is shown as a control sequence  106 , which is processed in the data transmission controller  54 . The control sequence is processed in the direction of arrow  108 . The control sequence  106  consists substantially of four control blocks. A first block  110  contains commands for the sequence of operation of the data transmitting. A second block  112  contains the start time, when data are to be transmitted. A third block  114  contains the respective start address of the data sequence to be transmitted in data memory  62 , and block  116  contains the magnitude of the data sequence to be transmitted. Often, the control sequence consists of many consecutive control sequences. This is symbolized by dots  118 .