Patent Publication Number: US-2009234997-A1

Title: Connecting device for connecting industrial apparatuses to a communication bus

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a connecting device for connecting industrial apparatuses to a communication bus. 
     The invention preferably applies in the industrial field, typically whenever a plurality of machines (for any type of working) are distributed inside the same structure and are connected to each other through a communication bus. 
     It is known that, above all in the industrial field, structures are presently used in which a plurality of machines are positioned within the same area (a shed or similar place, for example) and are connected to each other by means of a communication bus. 
     Through the same bus a communication with a control unit can also be obtained, which unit is entrusted with the task of dealing with operation of the machines associated therewith. 
     Within this technical field, the present invention aims at making available a connecting device for connecting industrial apparatuses to a communication bus which is able to improve communication between the different machines and between the machines and the control unit. 
     SUMMARY OF THE INVENTION 
     In particular, it is an object of the present invention to provide a connecting device enabling the already present communication networks to become redundant. 
     Another object of the invention is to provide a connecting device suitable for application to already existing systems without particular modifications and adaptation operations being required. 
     It is a further object of the invention to make available a connecting device that is able to add new operating activities to the presently existing communication systems. 
     It is a still further object of the invention to provide a connecting device that is capable of adapting itself in a simple and quick manner to possible modifications made to the communication system with which the device itself is associated. 
     The foregoing and still further objects are substantially achieved by a connecting device for connecting industrial apparatuses to a communication bus, in accordance with the features recited in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will be best understood from the detailed description of a preferred but not exclusive embodiment of the invention. This description is set out hereinafter with reference to the accompanying drawings, given by way of non-limiting example, in which: 
         FIG. 1  is a block diagram of a connecting device in accordance with the invention; 
         FIG. 2  is a block diagram of a communication system comprising the device shown in  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the drawings, a connecting device in accordance with the invention has been generally identified with 1. 
     Device  1  is used for connecting a respective industrial apparatus  2  to a communication bus  60 . 
     Industrial apparatuses  2  may for instance comprise actuating members (such as motors, inverters, actuators, etc.), detecting devices (such as pressure sensors, temperature sensors, etc.), machinery, control devices, and so on. 
     Also included among apparatuses  2 ,  2   a  can be a control apparatus  2   a  designed to control operation of the remaining apparatuses  2  connected to bus  60 . 
     By way of example, the control apparatus  2   a  can be a PLC, through which the control logic of the network consisting of apparatuses  2  is obtained. 
     The protocol used on bus  60  is preferably a so-called fieldbus and can be a modbus, profibus, etc. protocol, for example. 
     Each apparatus  2 ,  2   a  is connected to bus  60  by means of a respective device  1 , as diagrammatically shown in  FIG. 2 . 
     The structure of each of the devices  1  employed in such a system will be now described. 
     Device  1  ( FIG. 1 ) comprises a first physical interface  10  for connection with bus  60 ; the first interface  10  enables device  1  to receive signals from bus  60 , and/or to send signals to the bus  60  itself. 
     The first interface  10  is of the “physical” type, which means that, in order to enable a connection to be made with bus  60 , the first interface  10  and bus  60  must be in contact with each other. 
     Practically, the first interface  10  defines a cabled connection with bus  60 . In more detail, the first interface  10  is provided for engagement with a corresponding interface  61  of bus  60 . 
     By way of example, the first interface  10  can be of the serial type (RS232, RS485), of the ethernet type, etc. 
     Device  1  further comprises a second physical interface  20 , for connection with the respective apparatus  2 ,  2   a.    
     The second interface enables device  1  to receive signals from apparatus  2 ,  2   a , and/or to send signals to the apparatus  2 ,  2   a  itself. 
     Each apparatus  2 ,  2   a  is preferably provided with a control unit, entrusted with the task of dealing with the apparatus operation and allowing a communication with one or more of the other apparatuses at least through said bus  60 . 
     Like the first interface  10 , the second interface  20  too is of the “physical” type, which means that it defines a cabled connection between device  1  and the respective apparatus  2 ,  2   a , of such a nature that device  1  and the respective apparatus  2 ,  2   a  must be substantially in contact with each other for enabling the second interface  20  to communicate with apparatus  2 ,  2   a.    
     In more detail, the second interface  20  is provided for engagement with a respective interface  3  of apparatus  2 ,  2   a . By way of example, the second interface  20  can be of the serial type (RS232, RS485), of the ethernet type, etc. 
     Preferably the first interface  10  is substantially equal to interface  3  of apparatus  2 ,  2   a  associated with device  1 , and the second interface  20  is substantially equal to interface  61  of bus  60 . This means that device  1  is connected to apparatus  2 ,  2   a  in the same manner as bus  60  can be connected to the apparatus  2 ,  2   a  itself. In other words, taking into account a system in which apparatus  2 ,  2   a  is directly connected to a bus  60  through a physical interface, it is possible to disconnect apparatus  2 ,  2   a  from bus  60 , to connect apparatus  2 ,  2   a  to the second interface  20  of device  1 , and finally to connect the first interface  10  of device  1  to the interface  61  of bus  60 . 
     Device  1  further comprises a processing unit  40  interposed between the first and second interfaces  10 ,  20 . 
     As it will become apparent from the following, the processing unit  40  allows a logical bypass between the first and second interfaces  10 ,  20  to be carried out, so that apparatus  2 ,  2   a  can communicate with bus  60  as if device  1  were not interposed and apparatus  2 ,  2   a  were directly connected to bus  60 . 
     In more detail, the processing unit  40  comprises a first reception module  41  for receiving at least one main signal  100  from bus  60 , through the first interface  10 . 
     The processing unit  40  further comprises a first transmission module  42  for generating at least one corresponding auxiliary signal  110  to be sent to apparatus  2 ,  2   a  through the second interface  20 . 
     The auxiliary signal  110  is substantially equal to the main signal  100 , so that signals coming from bus  60  and received by device  1  are re-proposed in a substantially equal manner to apparatus  2 ,  2   a.    
     It is to be noted that “equal signals” or “substantially equal signals” means signals having the same information contents, offered through the same protocol and according to the same electrical features, so that reception either of a given signal or of a signal equal thereto, is quite indifferent for a hypothetical device adapted to receive such signals. 
     The processing unit  40  further comprises a second reception module  43  for receiving at least one primary signal  120  from apparatus  2 ,  2   a , through the second interface  20 . 
     The processing unit  40  also comprises a second transmission module  44  for generating at least one corresponding secondary signal  130  to be sent to bus  60  through the first interface  10 . 
     The secondary signal  130  is substantially equal to the primary signal  120 . 
     In this manner device  1  allows a two-way communication between apparatus  1  and bus  60  which in a substantially identical manner reproduces the communication that would take place if apparatus  2 ,  2   a  were directly connected to bus  60 . 
     It will be appreciated that connection between the first and second interfaces  10 ,  20  is not therefore made through a physical direct connection, but through the processing unit  40  receiving signals from the first interface  10  and generating substantially identical new signals, that will be then supplied to the second interface  20  so as to enable an actual communication to bus  60  of apparatus  2 ,  2   a.    
     The same is true for data that from apparatus  2 ,  2   a  reach the second interface  20  to be then sent to the first interface  10  and therefrom to bus  60 . 
     Device  1  in addition comprises a third interface  30  associated with the processing unit  40  to receive/send wireless signals. 
     By way of example, the third interface  30  can be provided with a Wi-Fi, Wi-Max, Zigbee, Bluetooth module, etc. 
     As will be better clarified in the following, the third interface  30  can be advantageously utilized to cause the communication system obtained through bus  60  to become redundant so that communication from and to apparatus  2 ,  2   a  is made more reliable. 
     Preferably the processing unit  40  further comprises an auxiliary transmission module  45  to send at least one first wireless signal  140 , substantially having the same contents as said primary signal  120 , through the third interface  30 . 
     The second reception module  43  receives the primary signal  120 , and is operatively active on the second transmission module  44  and on the auxiliary transmission module  45  to selectively cause generation of the secondary signal  130  and/or generation of the first wireless signal  140 . 
     In a first operating condition, the second reception module  43  causes generation of both the secondary signal  130  and the first wireless signal  140 ; preferably the secondary signal  130  and the first wireless signal  140  have the same contents. In this case, the device  1  can be used to enable the communication network to become redundant. 
     In another operating condition, the second reception module  43  causes generation of the secondary signal  130  only, and does not cause generation of the first wireless signal  140 . 
     In a further operating condition, the second reception module  43  causes generation of the first wireless signal  140 , and does not cause generation of the secondary signal  130 . 
     In a further operating condition, the second reception module  43  can cause the generation of either the first wireless signal  140 , or the secondary signal  130 , or both of them, or none of them, by analyzing the content of the primary signal  120  and applying any appropriate configured rule. 
     Therefore, according to the operating condition in which the second reception module  43  is set, the contents of a primary signal  120  can be re-transmitted through the first interface  10  (second signal  130 ) and/or through the third interface  30  (first wireless signal  140 ). 
     Preferably the second reception module  43  can be driven between the aforementioned operating conditions through a selection device (not shown) which can be actuated by a user, such as a dip switch, for example. 
     In addition or as an alternative, the second reception module  43  can be driven between the aforementioned operating conditions via software, by a proper digital command or instruction sent to the device  1 , and in particular to the second reception module  43 . 
     In a preferred embodiment, the digital command or instruction can be sent to the device  1  by means of a wireless technology, and in particular through the third interface  30 . 
     Preferably, the processing unit  40  also comprises a third reception module  46  for receiving at least one second wireless signal  150 , through the third interface  30 . 
     In a preferred embodiment, the second wireless signal  150  has substantially the same contents as the main signal  100 . 
     Preferably, the processing unit  40  also comprises a third transmission module  47  for generating a corresponding transmission signal  160  to be sent to apparatus  2 ,  2   a  through the second interface  20  and substantially having the same contents as the second wireless signal  150 . 
     The third reception module  46  provides the third transmission module  47  or causes the third transmission module  47  to be provided with a cabled signal  150 ′ having the same contents as the second wireless signal  150 . 
     In this manner, the same signals addressed to apparatus  2 ,  2   a  can be received both through physical connection and through wireless connection and, likewise, the signals generated by apparatus  2 ,  2   a  can be sent both through physical connection and through wireless connection. 
     Advantageously the processing unit  40  further comprises a selection module  48  active on the first transmission module  42  and on the third transmission module  47  to cause generation of the auxiliary signal  110  and/or of the transmission signal  160 . 
     In case the device  1  is used to enable the network that apparatus  2 ,  2   a  belongs to become redundant, the contents of the main signal  100  and of the second wireless signal  150  can be the same; therefore the selection module  48  will be able to compare the contents of the main signal  100  and of the second wireless signal  150  and, in case such content is the same, generation of only one between the auxiliary signal  110  and transmission signal  160  will be caused. 
     It is to be noted that the contents taken into consideration by the selection module  48  may preferably comprise a unique identifier of the aforementioned signals; thus, in case the main signal  100  and second wireless signal  150  are associated with the same identifier (i.e. the main signal  100  and the second wireless signal  150  are “the same signal”, only transmitted in two different ways), the information contained in such signals may be sent to the apparatus  2 ,  2   a  only once (through the auxiliary signal  110  or the transmission signal  160 ). 
     According to a different operating condition, the selection module  48  takes into consideration the main signal  100  only and causes generation of the auxiliary signal  110  only; the second wireless signal  150  is not taken into consideration and the transmission signal  160  is not generated. 
     According to a further different operating condition, the selection module  48  takes into consideration the signal provided by the third reception module  46  and cause generation only of the transmission signal  160  only; the main signal  100  is not taken into consideration and the auxiliary signal  110  is not generated. 
     According to a further different operating condition, the selection module  48  takes into consideration both the main signal  100  and the signal  150 ′ provided by the third reception module  46 , and causes generation of both the auxiliary signal  110  and of the transmission signal  160 ; no selection between the latter will be performed, and the contents of the received signals will not be taken into consideration. 
     In particular the main signal  100  may have different contents than the cabled signal  150 ′. 
     The selection module  48  can superimpose a semantic filter on the previously defined operating conditions by allowing or inhibiting the generation of the auxiliary signal  110  and/or the transmission signal  160  by analyzing the content of the primary signals  100  and/or signal  150 ′, and applying any appropriate configured rule. 
     The selection module  48  can be set up in one of the operating conditions described above by means of a selection device (not shown), which can be actuated by a user, such as for example a dip switch. 
     In addition or as an alternative, the selection module  48  can be set up in one of the operating conditions described above via software, by a proper digital command or instruction sent to the device  1 , and in particular to the selection module  48 . 
     In a preferred embodiment, the digital command or instruction can be sent to the device  1  by means of a wireless technology, and in particular through the third interface  30 . 
     Preferably, the wireless signals sent/received by the third interface  30  are short range wireless signals. 
     It is to be noted that in the present context and in the following claims, the expression “short range” refers to wireless networks where technologies are used in which the maximum connection distance is geographically restricted and can be preferably included between some meters and some ten kilometers. 
     The short range wireless networks are not natively connected to each other and do not natively form remote connections. The short range wireless networks substantially are wireless LANs (Local Area Networks). 
     Therefore, a short range wireless signal will be a signal by which two devices linked to the same short range network communicate. 
     By way of example, with reference to the present invention, short range wireless networks of the Wi-Fi, Wi-Max, Zigbee, Bluetooth, etc. types can be utilized. 
     Preferably, for controlling wireless communication between apparatuses  2 ,  2   a , use of a wireless router  70  is provided ( FIG. 2 ). 
     Preferably, each device  1  is uniquely identified by a respective wireless identifier WID, i.e. a parameter enabling each device  1  to be detected within the wireless network. 
     Preferably, each apparatus  2 ,  2   a  is uniquely identified by a physical identifier PID, i.e. a parameter enabling each apparatus  2 ,  2   a  to be detected within the “physical” network consisting of apparatus  2 ,  2   a  and bus  60 . 
     Said router  70  therefore can comprise a memory  71  into which the wireless identifiers WIDs of each device  1  are stored and in which each wireless identifier WID is associated with the physical identifier PID of apparatus  2 ,  2   a  connected to the device  1  detected by the respective wireless identifier WID. 
     In other words, the wireless router  70  allows the different apparatuses  2 ,  2   a  and devices  1  associated therewith to be detected within the wireless network. 
     In more detail, the control apparatus  2   a , preferably consisting of a PLC, comprises a first storage register  4  ( FIG. 2 ) containing the list of the physical identifiers PIDs of all apparatuses  2 , i.e. the identifiers through which apparatuses  2  can be detected in the physical connection via bus  60 . 
     In addition, each apparatus  2  is preferably provided with a second storage register  5  into which its own physical identifier PID is stored together with the physical identifier of the control apparatus  2   a.    
     Preferably each device  1  is provided with a storage register  6  into which its own wireless identifier WID and the wireless identifier of router  70  are stored. 
     When the control apparatus  2   a  must send a signal (a control, command, setting, query signal, etc., for example) to another apparatus  2 , the following steps are carried out:
         the control apparatus  2   a  generates the primary signal  120  and, through its own second interface  20 , its own first interface  10  and bus  60 , sends the corresponding secondary signal  130 , incorporating the physical identifier PID of the addressee apparatus; this identifier is suitably selected in the first storage register  4 ;   the control apparatus  2   a , through the third interface  30  of device  1  associated therewith, sends a first wireless signal  140  addressed to router  70  (i.e. incorporating the wireless identifier of the router  70  itself), and comprising the physical identifier of the addressee apparatus  2 , together with other data contained in the primary signal  120 ; practically, the first wireless signal  140  contains the same information as contained in the primary signal  120 , to which the wireless identifier WID of the wireless router  70  is added;   device  1  associated with the addressee apparatus  2  receives a main signal  100  (i.e. the secondary signal transmitted from the control apparatus  2   a ) through its own first interface  10 , and sends the corresponding auxiliary signal  110  to the addressee apparatus  2 , through the second interface  20 ;   router  70  receives the first wireless signal  140  transmitted by the control apparatus  2   a ; note that all devices  1  of the other apparatuses  2  will “hear” such a wireless signal but will interpret it as a signal not addressed to themselves, since they do not recognize the addressee wireless identifier WID incorporated therein;   router  70  retrieves, in its own memory, the wireless identifier WID of device  1  associated with the addressee apparatus  2  detected by the wireless signal received (it is to be remembered that the wireless signal received incorporates, among other data, the physical identifier PID of the addressee apparatus  2 );   router  70  generates a new wireless signal, referred to as second wireless signal  150 , incorporating the wireless identifier WID of the device  1  associated with the addressee apparatus  2 ;   device  1  associated with the addressee apparatus  2  receives, through its own third interface  30 , the second wireless signal  150  generated by router  70  and addressed to said apparatus  2 ; device  1  is able to establish that it is the addressee of such a signal  150  because it knows its own wireless identifier and compares it with the wireless identifier incorporated into the signal from router  70 ;   the second wireless signal  150  received by device  1  associated with the addressee apparatus  2  is then sent to the addressee apparatus  2  through the second interface  20 .       

     In a quite dual manner, when apparatus  2  must send a signal to the control apparatus  2   a  the following steps are performed:
         generating and transmitting a physical signal by the sender apparatus  2  through bus  60 ; this signal incorporates the physical identifier PID of the control apparatus  2   a ; by way of example, the signal generated by the sending apparatus  2  can be a detection signal, an alarm signal, a notification signal, an asynchronous notification signal, etc.;   wireless repeating this physical signal and sending it through the third interface of device  1  associated with the sender apparatus  2 ;   receiving the physical signal by the control apparatus  2   a  through bus  60  and the first and second interfaces  10 ,  20  of the device  1  associated with the control apparatus  2   a;      receiving by router  70 , the wireless signal generated by the device  1  associated with the sender apparatus  2 ;   selecting by router  70 , the wireless identifier of the device  1  associated with the control apparatus  2   a , and sending a wireless signal substantially having the same contents as the received signal;   receiving by the device  1  associated with the control apparatus  2   a , the wireless signal generated by router  70  and sending the contents of this signal to the control apparatus  2   a , by the device  1  itself.       

     It should be appreciated that the above described sequence of steps is carried out in case the device  1  is used to enable the communication network to become redundant. 
     Should the device  1  be used for different purposes than redundancy (see different operating conditions of the selection module  48  and/or of the second reception module  43 ), only some of such steps will be performed. 
     Advantageously, the processing unit  40  can be provided with a first identification module  49  for detecting in the main signal  100  received, a parameter representative of the fact that such a main signal  100  is to be sent to apparatus  2 ,  2   a  associated with said device  1 . 
     This parameter can be the above mentioned physical identifier PID of apparatus  2 ,  2   a  associated with device  1 . 
     It is to be pointed out that this identification step can be carried out both in an independent manner by apparatus  2  (therefore without the device  1  being provided with the first identification module), and by the processing unit  40  through said first identification module  49 . 
     At all events, device  1  and/or apparatus  2  associated therewith are provided with a suitable storage register in which the physical identifier of this apparatus  2  is stored, so that the recognition step can be correctly performed. 
     Advantageously, the processing unit  40  can be provided with a second identification module  50  to detect in the second wireless signal  150  received, a parameter representative of the fact that its signal is to be sent to the apparatus associated with the device  1  in question. 
     Preferably, this parameter is the above mentioned wireless identifier WID of device  1 . 
     In this connection, device  1  (and in particular the processing unit  40 ) can be conveniently provided with a storage register in which the wireless identifier thereof is stored, so as to suitably perform the mentioned recognition step. 
     In a preferred embodiment, the processing unit  40  further comprises a first control module  51  to control whether the first interface  10  is connected to the corresponding interface  61  of bus  60 . 
     The control carried out by the first control module  51  can be of the periodical type or also of a substantially continuous type. 
     This control aims at avoiding the first interface  10  being taken into account for sending signals (secondary signal  130 ) and/or receiving signals (main signal  100 ), so as to save the device  1  resources in terms of electric power and computational activity. 
     Advantageously, the processing unit  40  may further comprise a second control module  52  to control whether the third interface  30  is connected to a corresponding wireless network for receiving/transmitting wireless signals. 
     The control carried out by the second control module  52  can be of the periodical type or also of a substantially continuous type. 
     This control aims at avoiding the third interface  30  being taken into account for sending signals (first wireless signal  140 ) and/or receiving signals (second wireless signal  150 ), so as to save the device  1  resources in terms of electric power and computational activity. 
     The first and/or third interface  10 ,  30  can therefore be monitored, and possibly excluded from the sending/receiving operations; monitoring preferably goes on also when one or both interfaces  10 ,  30  are deactivated, so that as soon as an interface becomes ready for use again (i.e. the first interface  10  is physically connected to a bus  60  and/or the third interface  30  is linked to a wireless network), the same interface is utilized again for sending signals and being inquired for possible receptions. 
     In a further embodiment, in addition or as an alternative to the different devices  1 , the network formed by apparatuses  2 ,  2   a  and bus  60  can be provided with an auxiliary device having a physical interface through which it is connected to bus  60  and a wireless interface for long range wireless connection. 
     It is to be pointed out that in the present context the expression “long range” refers to wireless networks where technologies are used in which the maximum connection distance is geographically substantially boundless. 
     The long range wireless networks can be connected to each other for natively obtaining remote connections. 
     The long range wireless networks are substantially wireless WANs (Wide Area Networks). 
     Therefore, a long range wireless connection will be obtained through signals enabling a communication between two devices linked to the same long range network and positioned without any considerable limitation in their mutual distance. 
     For instance, the wireless interface of said auxiliary device may comprise a GPRS module, a UMTS module, etc. 
     Therefore through the auxiliary device it is possible to carry out a remote control of the whole operation of the network formed by apparatuses  2 ,  2   a  and bus  60  and to supply all related information to a remote management unit. 
     Practically, the auxiliary device, due to the connection allowed by its first interface, is “seen” by apparatuses  2 ,  2   a  as a further apparatus connected to bus  60 . 
     The auxiliary device however will have a different functional character, not of the operating type like the other apparatuses  2 ,  2   a , but of the “connective” type to carry out the above described long range connectivity. 
     It is to be noted that should a short range wireless network be present, for connection between apparatuses  2 ,  2   a , the auxiliary device could be provided with a first wireless interface for a short range connection with the wireless network of which also devices  1  associated with apparatuses  2 ,  2   a  are part, in combination with said second interface for long range wireless connections. 
     Please note that processing unit  40  included in device  1  has been disclosed as comprising a plurality of separate modules only for sake of clarity and for properly describe the functions that the same processing unit  40  can carry out. 
     Such modules are not necessarily to be considered as separate hardware modules. 
     Such modules can be realized as software modules, adapted to perform the above described functions when loaded in the processing unit  40 , so that the same processing unit can be realized as a single electronic device. 
     The invention achieves important advantages. 
     First of all, through the device of the invention communication between the different apparatuses, and in particular between the slave apparatuses and the control apparatus, is greatly improved. 
     In addition, due to the fact that the communication can be made redundant through the device of the invention, safety and reliability of the network are increased. 
     Another advantage is found in the fact that the device being the object of the invention can be applied to already existing systems without particular modifications and adaptation operations being required. 
     Another advantage consists in that, should the whole system be submitted to modifications (of structural character for example, in terms of variation in the apparatus arrangement, etc.) the device of the invention is perfectly able to adapt itself without any particular adaptation operation being required.