Abstract:
A mounting rail bus system for supplying power voltage and data signals to a plurality of modules, including a plurality of longitudinally-arranged bus devices mounting the modules in parallel spaced transverse relation on a mounting rail, each of the bus devices including a printed circuit board having parallel strip conductors for transmitting data signals, and a pair of power contact pins for transmitting a power voltage, characterized by the provision of a plurality of generally L-shaped double bushing contact elements have module bush segments for respectively connecting the strip conductors and the contact pins of the bus device with the associated module, and orthogonally arranged partner bush segments for connecting together the strip conductors and pin contacts of adjacent bus devices, respectively, whereby power voltage and data signals are transmitted from the bus device both to the associated module and to the adjacent partner bus device.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of the International application No. PCT/EP2011/056953 filed May 2, 2011, based on the German priority application No. DE10 2010 016 865.3 filed May 10, 2010. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     A mounting rail bus system for supplying power voltage and data signals to a plurality of modules, including a plurality of longitudinally-arranged bus devices mounting the modules in parallel spaced transverse relation on a mounting rail, each of the bus devices including a printed circuit board having parallel strip conductors for transmitting data signals, and a pair of power contact pins for transmitting a power voltage, characterized by the provision of a plurality of generally L-shaped double bushing contact elements have module bush segments for respectively connecting the strip conductors and the contact pins of the bus device with the associated module, and orthogonally arranged partner bush segments for connecting together the strip conductors and pin contacts of adjacent bus devices, respectively, whereby power voltage and data signals are transmitted from the bus device both to the associated module and to the adjacent partner bus device. 
     2. Description of Related Art 
     It has been proposed in the prior art to provide mounting rail bus systems having a mounting rail upon which one can mount modules that can be lined up next to each other in the manner of a series terminal, which are also referred to as bus partners, and a station bus that is arranged in the mounting rail by means of which the modules can be connected among each other and preferably also with a control or a gateway. The modules preferably in each case have their own electronics, which is connected to the module bus, and they serve, as a rule, for the connection of field units such as actuators, sensors, or initiators. 
     The station bus supplies the modules with electrical energy and transfers data and/or control signals to the modules from the modules or between them. 
     The continually growing requirement in control technology for example, in automation technology, results in a demand for mounting rail bus systems that are further optimized in terms of the number of parts, the number of partners, and a contact design. 
     The present invention was developed to provide an improved rail-mounted module system that avoids the above and other drawbacks of the prior module mounting systems. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a primary object t of the present invention to provide a mounting rail bus system for supplying power voltage and data signals to a plurality of modules, including a plurality of longitudinally-arranged bus devices mounting the modules in parallel spaced transverse relation on a mounting rail, each of the bus devices including a printed circuit board having parallel strip conductors for transmitting data signals, and a pair of power contact pins for transmitting a power voltage, characterized by the provision of a plurality of generally L-shaped double bushing contact elements have module bush segments for respectively connecting the strip conductors and the contact pins of the bus device with the associated module, and orthogonally arranged partner bush segments for connecting together the strip conductors and pin contacts of adjacent bus devices, respectively, whereby power voltage and data signals are transmitted from the bus device both to the associated module and to the adjacent partner bus device. 
     According to another feature of the invention, address means are provided for identifying the modules that are associated with the various bus devices, respectively, use being made, for each device, of a double bushing contact element of the present invention. 
     According to a more specific object of the invention, each bus device has contact pins for the transmission and/or manipulation of electrical power supply output and/or with at least one printed circuit board with strip conductors for the transmission of electrical data and/or control signals with preferably reduced power when compared to the power supply output. Here, every contact pin and every strip conductor of the printed circuit board is in each case connected with a double bushing contact element. All double bushing contact elements are, in particular, made identical and can be used both for power transmission and for data transmission, something that results in a rather small multiplicity of parts and reduces the system production costs. 
     Another advantage consists in the fact that the double bushing contact elements are made both for the transmission of electrical power supply and for the transmission of electrical data and/or control systems of a lesser power output. Therefore, they can be used both for the connection of the contact pins and strip conductors and for the electrical connection of a module which is to be allocated as bus partner. In that way, one can save construction space. A compact design also results when the second bushing segments of the double bushing contact element are arranged essentially orthogonally with respect to the first bushing segments that extend in the longitudinal direction along the mounting rail. 
     The double bushing contact element, for example, can be made as bent stamping and can have a foot and a connecting surface arranged opposite the foot. That creates a possibility for attachment, both on a contact pin and on a printed circuit board so that no additional adaptation measures are required. 
     Another compact design results on the basis of a plurality of the double bushing contact elements that are arranged next to each other, whereby the contact pins and the printed circuit board extend in a manner arranged next to each other in each bus member along the longitudinal direction of the mounting rail. 
     In another embodiment, the station bus is preferably, however, not necessary made also as a mounting rail bus addressing system. The address elements can also be made for the digital manipulation of a signal, for example, frequency doubling, inter-pulse period ratio change, and the like. Here it must be emphasized that the address elements can be made as frequency division device with a determinable, preferably constant, divider factor. Here, for example, a digital signal, for example, a digital square wave signal with a constant frequency that is generated by a frequency generator, is put on the address elements that are connected in series. Each bus member influences this signal in a manner that makes it possible to recognize the total number of influencing bus members. 
     Particularly advantageous here is the digital utilization by means of a digital microcontroller and the attendant high degree of interference immunity. The number of bus members is limited only by a span of time that is specifically set for address recognition. For example, preference is given to a divider factor of 2. 
     The invention also relates to a method for addressing bus members of a bus system where the addressing is done with an above-described mounting rail bus system. 
     The invention furthermore relates to a method for signaling a composite error in an above-described mounting rail bus system. 
     Furthermore, the described address line (analog as well as digital) can be used for signaling a composite error. Suitable methods for this purpose in case of resistive addressing, for example, would be the periodic short-circuiting of the address signal against a return circuit. This periodic signal then is continued as a voltage change in all bus members. In case of digital addressing, the error report takes place by short-circuiting the digital signal by means of a bus partner. The bus members make sure that this short-circuit is passed on in both directions and that therefore no further addressing signal is produced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention will become apparent from a study of the following specification, when viewed in the light of the accompanying drawing, in which: 
         FIG. 1  is a perspective view of a first embodiment of mounting rail bus system according to the present invention; 
         FIG. 2  is a perspective view of two connected bus members of the mounting rail bus system when in the assembled condition according to  FIG. 1 ; 
         FIG. 3  shows two bus members according to  FIG. 1  when in the disconnected condition; 
         FIG. 4  is a perspective view of the bus members according to  FIG. 2  when in a partially disassembled condition; 
         FIG. 5  is a perspective illustration of the bus member conductor arrangement of a double bushing contact arrangement according to  FIG. 2 ; 
         FIG. 6  is a perspective view of an assembly of a contact pin with a double bushing contact element; 
         FIG. 7  is a detailed perspective illustration of the double bushing contact element of  FIG. 6 ; 
         FIG. 8  is a block diagram illustrating a station bus having a plurality of modules; 
         FIG. 9  is a block diagram illustrating the station bus with modules according to  FIG. 8  including an indication of the various voltages; 
         FIG. 10  is a circuit diagram of an addressing device of the station bus with modules according to  FIG. 8 ; 
         FIG. 11  is a perspective illustration of the bus member conductor structure according to  FIG. 5  including a portion of the addressing device according to  FIG. 10 ; 
         FIG. 11   a  is a circuit diagram of a portion of the addressing device of the bus member conductor structure according to  FIG. 11 ; 
         FIG. 12  is a perspective view, with certain parts broken away, of the connected bus members according to  FIG. 4  with the bus member conductor structure according to  FIG. 10 ; and 
         FIG. 13  is a circuit diagram with a further addressing device of the station bus with modules according to  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Functional units and structural elements with identical reference numbers indicate identical or similar functions. The following explanation relates to a particularly preferred exemplary embodiment to which, however, the invention is not restricted. 
     Referring first to  FIG. 1 , the mounting rail system  1  comprises a mounting rail  2  that in this case is made as a so-called top hat rail and that has a station bus  3  with at least two mutually connected bus members  6 . A module  4 , which in this case has various conductor connections (for example, terminal connections) and electronic switching functions that are not explained in any greater detail, can be stuck upon or inserted into the bus members and can be connected with the bus members. Module  4  is also referred to as bus partner of the station bus  3 . 
     Bus members  6  are arranged inside mounting rail  2 , for example, they are retained or clamped in a force-locking manner, and in each case, they have a plug-in site  5 , which essentially extends orthogonally with respect to mounting rail  2  and which is provided for the insertion of a module plug-in segment of module  4 . In  FIG. 1 , module  4  is shown in a position in which it engages with its underside already on mounting rail  2  and where the module plug-in segment  9  is already partly introduced into plug-in site  5 . Bus members  6  are connected with each other via plug-in connections of which in this case we can see on the front bus member  6  a power bushing seat  7  and a data bushing seat  8 . This will be explained in greater detail below. 
       FIG. 2  shows a perspective view of two connected bus members of the inventive mounting rail bus system  1  according to  FIG. 1 , and  FIG. 3  illustrates the two bus members according to  FIG. 2  in the disconnected position. 
     Bus members  6  can be plugged together in the longitudinal direction of mounting rail  2  and can be connected among each other. In this illustrated example, each bus member  6  has a housing  10  with a power bushing seat  7  (in this case, on the left side) and a data bushing seat  8 , and on the opposite side (in this case, on the right) a power plug seat  11  and a data plug seat  12 . In embodiments not illustrated, each bus member  6  can have either a housing  10  with only one power bushing seat  7  and one power plug seat  11 , or a housing  10  with only one data bushing seat  8  and one data plug seat  12 . The power bushing seat  7  of the left bus member  6  corresponds to the opposite power plug seat  11  of the right bus member  6  and the data bus seat  8  of the left bus  6  corresponds to the data plug seat  12  of the right bus member  6 . The power bus seat  7  and the data bushing seat  8  in each case can be plugged into corresponding plug-in seats  11  and  12  in the longitudinal direction of mounting rail  2 . In the process, power plug  16  and data plug  17 , which are arranged in plug seats  11  and  12 , in each case are introduced into corresponding power contact bushings  18  and data contact bushings  19  (see  FIG. 5 ), which are arranged in bushing seats  7  and  8 , and among each other in each case establish electrically conducting contacts. 
     Plug-in site  5  of a bus member  6  is formed by opposite module plug-in seat walls  13 , which are connected with housing  10  and located in between are module contact bushings  14  and  15  (see  FIGS. 4 and 5 ). The module plug seat walls  13  here are provided with guides that are not described in any greater detail and which ensure a definite and unambiguous association of the module plug segment  9  with the module contact bushings  14  and  15 . 
       FIG. 4  illustrates a perspective, partly open view of the connected bus member  6  according to  FIG. 2 . Here, in a part of the housing  10  of right bus member  6 , there is removed an area of the module contact bushings  14  and  15 . The module contact bushings  14  and  15  are subdivided into the module power contact bushings  14  and module data contact bushings  15 . The module power contact bushings  14  are connected with contact pins  21  and the module data contact bushings  15  are connected with a printed circuit board  22 . Such a bus member conductor structure  20  will now be described in conjunction with  FIG. 5 , which shows a perspective illustration of the bus member conductor structure  20  of the bus member  6  according to  FIG. 2 . 
     The bus member conductor structure  20 , which is arranged in housing  10 , has the printed circuit board  22 , which extends in the longitudinal direction of housing  10  and thus in the longitudinal direction of mounting rail  2 . Next to printed circuit board  22 , there are arranged here two contact pins  21 , which extend in the plane of the printed circuit board  22  parallel to the latter. 
     Printed circuit board  22  is provided with strip conductors  23 , which extend in the longitudinal direction of printed circuit board  22  from a contact element side  25  (in this case, on the left) to a plug-in edge  24  of the printed circuit board  22 . Here, plug-in edge  24 , with the terminal segments of the strip conductors  23  located on them, forms the data plugs  17 . Naturally, printed circuit board  22  can also be provided with strip conductors  23  on both sides. Also possible are multilayer printed circuit boards and printed circuit boards with integrated structural components and/or bus bars. The strip conductors  23  have a usual thickness consisting of copper and amounting to, for example, 35 μm and 70 μm, and are provided for the electrical conducting of relatively small current intensities, for example, for data transmission and/or control signals. 
     On the contact element side  25 , there is arranged in each case per strip conductor  23  a double bushing contact element  30 , and it is electrically connected, for example, soldered, with a corresponding strip conductor  23  via a connecting segment  26 . In this example, five double bushing contact elements  30  are attached next to each other laterally with respect to the longitudinal direction of printed circuit board  22 . A certain segment of each double contact element  30  can also be connected mechanically with printed circuit board  22  (see also  FIG. 11 ), for example, it can be glued or possibly soldered (in case of a double-sided platinum coating. 
     Contact pins  21  consist of a massive metal material, for example, a copper alloy or copper, and are provided for electrical power transmission, for example, with current intensities in the range from 1 A. to 2 A. On the right side, they have tips  28  that lie next to the plug-in edge  17  and that form the power plugs  16 . On their other end, in this case, left, the contact pins  21  are also—like the printed circuit board  22 —in each case connected with a double bushing contact element  30  in the power connection segments  27 . 
       FIG. 6  shows a perspective view of a contact pin  21  with a double bushing contact element  30 . The double bushing contact element  30  has first and second contact tongues  32 ,  33 , which will be explained in greater detail below and which can be placed upon a base body  31  or connected with it. In power connection segment  27  on the top of the left terminal area of contact pin  21 , the double bushing contact element  30  is attached with a foot  36  which in the extension of a second contact tongue  33  is bent over in the longitudinal direction of contact pin  21 , for example, it is welded on. On the reverse side of the left end of contact pin  21 , double bushing contact element  30 , with a contact connection segment  29  that is located on the base body  31  or a bottom segment  34  of the double bushing contact element  30 , is likewise attached in the same or similar manner as in the case of foot  36 , for example, it is welded on. 
     The double bushing contact element  30  will now be further explained on the basis of a perspective view given in  FIG. 7 . The double bushing contact element  30 , for example, is a bent stamping consisting of an electrically conducting material with resilient properties in the area of the first and second contact tongues  32 ,  33 . The contact tongues  32  and  33  in each case are opposite each other in the usual manner and are bent over at a right angle by the base body  31 . The vertical base body  31  has a pair of bent parallel spaced horizontal wing portions  34  and  37 ′ that carry the resilient contact tongues  32  of the first bushing segment  38 , and a pair of bent parallel spaced vertical wing portions  35  and  37  that carry the resilient contact tongues  35  and  37 . The lower end of the vertical wing portion  35  terminates in a horizontal foot portion  36  having a lower fastening surface  36 ′, and the horizontal wing portion  34  has and extension provided with and upper fastening surface  34 ′. 
     Here, the first contact tongues  32  form a first bushing segment  38  with mutually adjacent or superposed rounded terminal segments which in the case of connected bus member  6  (see  FIGS. 2 and 3 ) is plugged together and engages the strip conductors  23  of printed circuit board  22  or the segments with the tips  28  of the contact pins  21  of the other bus member  6 . The lower first contact tongue  32  is lengthened in the longitudinal direction of printed circuit board  22  (see  FIG. 5 ) or of contact pin  21  (see  FIG. 6 ) in order to form the bottom segments  34  on whose right end there is a connecting surface  34 ′, which forms the contact connection segment  29  (see  FIG. 6 ) or a connection segment to the underside of printed circuit board  22  (see  FIG. 5 ). The opposite first contact tongue  32  is extended with wing portion  37 ′ that runs parallel to the bottom segment  34  but that is only about half as long. 
     Arranged at a right angle to the first contact tongues  32 , which form the first bushing segment  38 , are the two contact tongues  33  that are likewise canted over and that form a second bushing segment  39 . Here, the left second contact tongue  33 , similar to the first upper contact tongue  32 , is extended downward with a wing portion  37 . The other opposite contact tongue  33  extends in a wing portion  35  downwardly and is bent to define the foot portion  36 . Foot portion  36  has an underside surface  36 ′ fastened upon contact pin  21 , or it is attached in this manner upon a strip conductor  23  of printed circuit board  22 . 
     The second bushing segment  39  is provided for the contacting of a corresponding segment, for example, strip conductor or contact pin of the module plug-in segment  9  of module  4  (see  FIG. 1 ). The bushing segments  38  form the power contact bushings  18  and the data contact bushings  19  of the bus member conductor structure  20  according to  FIG. 5 , whereby the bushing segments  39  form the module power contact bushings  14  and the module data contact bushings  15  of the bushing member conductor structure  20  according to  FIG. 5 . All double bushing contact elements  30  are identical. 
     In another embodiment of the mounting rail bus system  1  according to  FIG. 1 , the latter has an addressing device  40 , which is described in conjunction with  FIG. 8 .  FIG. 8  shows a block diagram of a station bushing  3  with modules  4 . Modules  4  are connected with each other electrically via the station bushing  3 . 
     Station bus  3  includes several identical plug-in sites for individual modules  4 . In this example, we show five positions P 1  to P 5  for these plug-in sites, whereby position P 4  is not assembled. 
     In order that modules  4  of a station bus  3  (for example, a station) can communicate with each other, they need an address which here is predetermined by an addressing device  40  that will be described in greater detail below. 
       FIG. 9  shows the block diagram of station bus  3  with modules  4  according to  FIG. 8  with voltage indications to explain the principle of the addressing device  40 . An address is made available to the associated modules  4  as an analog voltage value at particular address taps  30 ′ (see  FIG. 10 ). Each module  4  determines an address volume UA that belongs to it toward a common return line  41  and can determine its address as a multiple of an individual voltage UE that is applied between adjacent address taps  30 ′. Here it applies that all individual voltages UE per module  4  are equally large. The address is obtained as follows:
 
Address= UA/UE   (1)
 
whereby: UE=1×R, which will be explained in greater detail below.
 
     In this connection,  FIG. 10  shows a circuit diagram of an addressing device  40  of the station bus  3  with modules  4  according to  FIG. 8 , wherein n plug-in sites are shown with positions P 1  to Pn. At each position Pi, there is arranged an address element  42 . This means that each bus member  6  is equipped with such an address element  42  at a corresponding position Pi. In this example, address element  42  is a resistance R (R 1  to Rn). These resistances R 1  to Rn are electrically connected in series, whereby they are connected via a supply line  44  running via a supply plug  46  with a pole of a constant current source  43  that supplies a current I. The other pole of constant current source  43  is connected with the return line  41  via a bridge conductor  45  with the other end of the series circuit of the resistances R 1  to Rn. Each plug-in site of station bus  3  is a bus member  6  with an addressing bushing  19 ′ and a strip conductor segment  23 ″ (see  FIGS. 11 and 12 ). The addressing bushing  19 ′ is connected with the address tap  30 ′. Thus, the individual voltage UE is here tapped between address tap  30 ′ and the strip conductor segment  23 ″ or via the particular resistance Ri. The particular address voltage UA can be determined between the address tap  30 ′ and the return line  41 . The return line  41  is run via a strip conductor  23 . 
     By means of the constant current source  43 , we make sure that always the previously defined current I will flow with sufficient accuracy through the series circuit of the resistances R 1  to Rn, which form a voltage divider. Assuming we have identical resistance values for resistances R 1  to Rn and identical current, UE in each case will be equally large:
 
 UE=Ri×I   (2)
 
 UAi=Ri×i×I   (3)
 
     For example, with: 
     I=1 mA, Ri=1.0 kΩ and i=10 (10 plug-in sites). 
     we now get UE at 1 V. From (1), (2) and (3), we get the following addresses for the positions P 1  to P 10  according to Table 1: 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Position 
                 UA [V] 
                 UE [V] 
                 Address 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 P1 
                 1 
                 1 
                 1 
               
               
                   
                 P2 
                 2 
                 1 
                 2 
               
               
                   
                 P3 
                 3 
                 1 
                 3 
               
               
                   
                 P4 
                 4 
                 1 
                 4 
               
               
                   
                 P5 
                 5 
                 1 
                 5 
               
               
                   
                 P6 
                 6 
                 1 
                 6 
               
               
                   
                 P7 
                 7 
                 1 
                 7 
               
               
                   
                 P8 
                 8 
                 1 
                 8 
               
               
                   
                 P9 
                 9 
                 1 
                 9 
               
               
                   
                 P10 
                 10 
                 1 
                 10 
               
               
                   
                   
               
             
          
         
       
     
       FIG. 11  shows a perspective illustration of the bus member conductor structure  20  according to  FIG. 5  with a component of the addressing device  40  according to  FIG. 10 .  FIG. 11   a  illustrates a circuit diagram of the component of the addressing device  40  of the bus member conductor structure  30  according to  FIG. 11 . 
     The strip conductor segment  23 ″ of the printed circuit board  22  forms the plug-in segment to the next bus member  6  or to the bridge  45  (see  FIG. 10 ). The strip conductor  23 ″ connects the plug-in segment with the address element  42 , which in this case is made as a resistance in the SMD (surface mounted device) manner and which is attached upon the printed circuit board  22 . The resistance or the address element  42  is then connected via another strip conductor segment  23 ″′ with the address tap  30 ′ (double bushing contact component element) in the shape of a module address bushing  15 ′ and the addressing bushing  19 ′. The return line  41  and the bridge  45  are not shown but can be easily visualized in that the return line  41  is another strip conductor  23  and bridge  45  is inserted on the data contact bushings  19  of a bus member  6  at one end of the station bus  3 . A constant current source  43  is connected at the other end of station bus  3 . 
       FIG. 12  shows a perspective, partly open view of the connected bus member  6  according to  FIG. 4  with the bus member conductor structure  20  according to  FIG. 10 . It is clearly recognizable that the address element  42  in the shape of an SMD component takes up very little space and is arranged in the bus member conductor structure  20  of a bus member  6 . When printed circuit board  22  is a printed circuit, the address element  42  can be included in the establishment of the printed circuit board layout. 
     Finally,  FIG. 13  shows a circuit diagram of another addressing device of the station bus with modules according to  FIG. 8 .  FIG. 13  is structured similar to  FIG. 10 , and therefore only the differences will be explained. A frequency generator  43 ′ supplies a signal with a previously determinable constant frequency f, for example, a digital rectangular signal that is only indicated in  FIG. 13 . The frequency range of frequency f is so adapted that a reliable and trouble-free addressing is possible, for example, the frequency can be in the range of 4 MHz. As address element  42 ′, we use here the frequency divider devices that in each case have a specific divider factor TF, for example, TF=½. This means that the frequency f that is fed in the supply line plug  46  at the address tap  30 ′ multiplied with the divider factor  14  as address frequency fA 1  amounts to half of frequency f (example: f=4 MHz; TF=½; fA 1 =2 MHz). At the other address taps  30 ′, there is then continually applied in each case half the frequency of the particular input frequency as address frequency fA 1 . In other words, the pulse time of the rectangular signals is doubled for each step. 
     Thus, the following addresses are obtained for positions P 1  to P 10  according to Table 2. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Frequency Measured 
                   
               
               
                   
                 Position 
                 by Module [kHz] 
                 Address 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 P1 
                 2000.00000 
                 1 
               
               
                   
                 P2 
                 1000.00000 
                 2 
               
               
                   
                 P3 
                 500.00000 
                 3 
               
               
                   
                 P4 
                 250.00000 
                 4 
               
               
                   
                 P5 
                 125.00000 
                 5 
               
               
                   
                 P6 
                 62.50000 
                 6 
               
               
                   
                 P7 
                 31.25000 
                 7 
               
               
                   
                 P8 
                 15.62500 
                 8 
               
               
                   
                 P9 
                 7.81250 
                 9 
               
               
                   
                 P10 
                 3.90625 
                 10 
               
               
                   
                   
               
             
          
         
       
     
     Here it is particularly advantageous that the particular signal of the pertinent address frequency fAn can be analyzed digitally, for example, by a microcontroller. That facilitates a high degree of trouble-free operation and reliability of address recognition. 
     The invention is not restricted to the above-explained exemplary embodiment. It is conceivable, for example, that one uses a conductor grid instead of the printed circuit board  22 . 
     The segments of the strip conductors  23  in the area of the plug-in edge  24  can be silver coated or gold coated in order to improve contacting, that is to say, to reduce a transmission contact resistance. This can also be the case with contact pins  21  in the area of tips  28 . 
     The address element  42  can also be another electronic component, for example, a condenser, an inductance, or also an active component, for example, a diode or a breakdown diode. Besides, the described address line (analog as well as digital) can be used for signaling a composite error. Suitable procedures on this score in the case of resistive addressing (addressing device according to  FIG. 10 ) by way of example are the periodic short-circuiting of the address signal at 0 V, that is to say, the address tap  30 ′ is connected with return line  41 , whereby, however, one can rule out any damage to the constant current source  43  or the frequency generator  43 ′. This periodic signal is then continued as a voltage change in all bus members. In case of digital addressing, as in the case of the further addressing device according to  FIG. 13 , the error report is transmitted by short-circuiting the digital signal by means of a bus partner. The bus members must make sure that these short-circuits are relayed in both directions and that no further addressing signal is thus generated. 
     An addressing or an address recognition procedure can also be performed with only one predetermined time interval. 
     While in accordance with the provisions of the Patent Statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that changes may be made without deviating from the invention described above.