Abstract:
To be able to achieve shorter communication cycles, the invention proposes a communication system which is able to connect field devices to a higher-order control device. For this purpose, a connection device is provided which is connectable to a higher-order control device via a transmission medium. The connection device has at least one first port and at least one second port, to each of which a field device may be connected. The connection device has at least one functional device which is switchable between at least one first port and at least one second port. The functional device is designed to generate output data intended for the second port in response to the input data arriving at the first port.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a communication system for connecting field devices, in particular sensors and actuators, to a higher-order control device. The invention further relates to a connection device which is suitable for use in such a communication system. 
       BACKGROUND OF THE INVENTION 
       [0002]    To be able to connect field devices within an automated system to a higher-order control device, for example a stored program control (SPC), in an efficient and cost-effective manner, standardized connection systems, known as IO-Link communication systems, have been known for quite some time. The IO-Link communication system is a standardized point-to-point connection system. IO-Link devices, which are primarily sensors, actuators, or combinations thereof, are connected via separate point-to-point connections to an IO-Link master, which in turn may be connected to an SPC. Each IO-Link device is connected to a separate IO-Link port of the IO-Link master. Depending on the configuration, the IO-Link ports function as digital inputs or outputs. In addition, IO-Link ports may be configured in such a way that they are able to establish cyclical communication with a connected IO-Link device. One task of the IO-Link master is to collect the input process data arriving at the ports from the connected IO-Link devices, and transmit them to the SPC via a higher-order field bus. The SPC has specialized functional devices which map the received input process data onto output process data. These output process data are subsequently sent from the SPC to the IO-Link master. The IO-Link master distributes the received output process data over the appropriate IO-Link ports, which then send output process data to the corresponding IO-Link devices. However, this communication cycle may take too long for some applications in which IO-Link input process data must be mapped more quickly onto IO-Link output process data. 
       SUMMARY OF THE INVENTION 
       [0003]    The object of the invention, therefore, is to provide a communication system and a connection device for connecting field devices to a higher-order control device, which allow input process data to be mapped more quickly onto output process data. 
         [0004]    A core concept of the invention is to provide a connection device which may be connected to a higher-order control device via a transmission medium. Multiple field devices may be connected to the connection device. The connection device has functional devices which map the input data received from at least one field device onto output data. The connection device subsequently transmits the output data to a destination field device. Since these processing steps are now carried out in the connection device itself, not in a higher-order control device, shorter communication cycles for exchanging process data may be achieved. 
         [0005]    Another core concept is that the connection device is a modified IO-Link master, and the field devices are IO-Link devices. 
         [0006]    Accordingly, a communication system for connecting field devices to a higher-order control device is provided. The communication system has a connection device which is connectable to a higher-order control device via a transmission medium. The connection device has at least one first port, to which a field device which generates input data is connected, and at least one second port, to which a field device which receives output data is connected. To be able to achieve shorter communication cycles and to allow the higher-order control device to be relieved of load, the connection device has at least one functional device which is switchable between at least one first port and at least one second port. The functional device is designed to generate output data intended for the second port in response to the input data arriving at the first port. 
         [0007]    It is noted at this point that the transmission medium may be a higher-order field bus, for example according to the Ethernet standard. “Input data” are understood to mean data that are generated by a field device and transmitted to the connection device, i.e., input data for the connection device. Similarly, output data are data that are transmitted by the connection device to a field device, and thus represent output data for the connection device. 
         [0008]    According to one advantageous embodiment, the communication system forms a modified IO-Link communication system in which the field devices are IO-Link devices, in particular sensors and actuators. In this case, the connection device communicates with the particular IO-Link devices via point-to-point connections according to the IO-Link protocol. In this embodiment, the connection device may also be regarded as a modified IO-Link master. 
         [0009]    To expand the potential uses for the communication system and to increase its flexibility, the connection device has multiple different functional devices and a programmable switching device. The switching device is designed in such a way that it is able to switch at least one functional device between at least one first port and at least one second port. 
         [0010]    It is noted at this point that the functional devices may implement different logical or arithmetic functions. It is also conceivable for the functional devices to be implemented as controllers, filters, closing delay devices, or opening delay devices. Depending on the desired application, it is possible to connect multiple functional devices in series so that the input data arriving at a port are able to run through a multistep processing operation before they are output to a field device. A desired overall function may thus be realized by the targeted interconnection of multiple functional devices. 
         [0011]    According to one advantageous refinement, the input data and output data contain process data which may be transmitted cyclically. The input data and output data are preferably sent in telegrams, which may also contain the port number of the corresponding first port or second port, as well as the length of the telegram or of the process data. The length may be expressed in bits or bytes. 
         [0012]    Accordingly, a connection device is provided which in particular is suitable for use in a communication system for connecting field devices to a higher-order control device. The connection device has at least one first port, to which a field device which generates input data is connectable, and at least one second port, to which a field device which receives output data is connectable. In addition, at least one functional device is provided which is switchable between at least one first port and at least one second port. The functional device is designed to generate output data intended for the second port in response to the input data arriving at the first port. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention is explained in greater detail below with reference to one exemplary embodiment, in conjunction with one figure. 
           [0014]      FIG. 1  depicts the salient components of a communication system  10  in accordance with an illustrative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    The figure shows a communication system  10 , for example in the form of an automated facility. The communication system  10  has a higher-order control device  20  which is connected to a transmission medium  30 , for example a field bus. Also connected to the field bus  30  is a connection device  40 , which with regard to the selected exemplary embodiment may also be referred to as an IO-Link connection device or modified IO-Link master. Solely for simplicity of the illustration, only one connection device  40  is shown. The connection device  40  may contain all functions of a standardized IO-Link master. However, to be able to transmit process data in shorter communication cycles within the communication system  10 , the modified IO-Link master  40  also has a plurality of different functional devices  50 ,  60 ,  70 ,  80 ,  90 ,  100 ,  110 . For example, the functional device  50  is implemented as an OR gate, the functional device  60  as an AND gate, the functional device  70  as an inverter, the functional device  80  as a controller, the functional device  90  as a filter, the functional device  100  as a closing delay device, and the functional device  110  as an opening delay device. In addition, the connection device  40  has multiple ports  130  through  136  which are configurable as input ports, and multiple ports  140  through  142  which are configurable as output ports. In the present example, a sensor is connected to each input port via a separate point-to-point connection. Thus, a sensor  150  is connected to the input port  130 , a sensor  151  is connected to the input port  131 , a sensor  152  is connected to the input port  132 , a sensor  153  is connected to the input port  133 , a sensor  154  is connected to the input port  134 , a sensor  155  is connected to the input port  135 , and a sensor  156  is connected to the input port  136 . Similarly, in the described example an actuator  160  is connected to the output port  140 , an actuator  161  is connected to the output port  141 , and an actuator  162  is connected to the output port  142 . The data which are provided by the sensors  150  through  156  and transmitted to the connection device  40  are referred to as input data, whereas the data transmitted from the connection device  40  to the actuators  160  through  162  via the respective output ports are referred to as output data. It is noted at this point that the input data are input process data, and the output data are output process data for controlling the actuators. 
         [0016]    According to the described exemplary embodiment, the output device  40  and the sensors and actuators connected thereto form a connection system, which may also be referred to as a modified IO-Link communication system. The sensors and actuators are implemented as IO-Link devices. 
         [0017]    Furthermore, the connection device  40  has a schematically illustrated programmable switching or control device  120 . The task of the switching device  120  is to lead the input data arriving at at least one input port  130  through  136  through one or more functional devices in dependence on the specified system implementation in order to obtain the desired output data. The output data are then supplied to a corresponding output port to which the destination actuator is connected. In the implementation of the connection device  40  by way of example, the input ports  130 ,  131 , and  132  are connected to the functional device  50 . In other words, the input process data arriving from the sensors  150 ,  151 , and  152  are linked in the functional device  50  according to an OR function. The input process data are preferably transmitted to the connection device  40  in telegrams in definable communication cycles. The input data present in a telegram may contain, in addition to the mentioned input process data, the port number of the particular input port, a bit offset, and the length of the telegram or the quantity of process data, expressed either in units of bits or bytes. Thus, the port number of the input port  130  is transmitted in a telegram provided by the sensor  150 , the port number of the input port  131  is transmitted in a telegram provided by the sensor  151 , and the port number of the input port  132  is transmitted in a telegram provided by the sensor  152 . The input port  130  or some other suitable device reads the input process data received in the telegram and transmits same to the input of the functional device  50 . In addition, the input port  130  or some other suitable device may check the port number of the input port  130  contained in the received telegram as to whether the received input process data have actually arrived from the correct source, i.e., the sensor  150 . The telegrams arriving from the sensors  151  and  152  are processed in a similar manner. 
         [0018]    At the output side the functional device  50  is connected to the output port  140 . As a result, the output process data generated by the functional device  50  are supplied to the output port  140 , and from there are transmitted to the actuator  160  in a communication cycle. The output process data are preferably transmitted to the actuator  160  in telegrams in definable communication cycles. The output data present in a telegram may contain, in addition to the mentioned output process data, the port number of the output port  140 , a bit offset, and the length of the telegram or the quantity of process data, expressed either in units of bits or bytes. The port number of the output port  140  contained in a telegram may be checked by the actuator  160  as to whether the received output process data are actually intended for the actuator  160 . 
         [0019]    The functional device  50  or some other device generates an outgoing telegram in which the output process data of the functional device  50 , the port number of the output port  140 , and a bit offset and optionally also the length of the telegram are written. The output telegram is then transmitted via the port  140  to the actuator  160 , which performs the desired operation in response to the corresponding output process data. 
         [0020]    The connection device by way of example also shows that the input ports  133 ,  134 , and  135  are connected by means of the switching device  120  to the functional device  60 , which processes the input data of the sensors  153 ,  154 , and  155  according to an AND operation. In the illustrated example, the functional devices  60  and  70  are connected in series. Therefore, the output data of the functional device  60  are supplied to the functional device  70 , which inverts the data received from the functional device  60 . The switching device  120  accordingly ensures that the input data arriving at the input ports  133 ,  134 ,  135  are processed in two stages, namely, initially in the functional device  60  and subsequently in the functional device  70 . The functional device  70  is connected to the output port  141  by means of the switching device  120 . This ensures that the output process data are transmitted from the functional device  70  to the destination actuator  161  via the output port  141 . 
         [0021]    According to one implementation by way of example, the switching device  120  also ensures that the input data arriving at the input port  136  from the sensor  156  pass through the controller  80 , and as corresponding output data are transmitted as output data to the actuator  162  via the output port  142 . Similarly, the remaining functional devices  90  through  110  may be switched between corresponding input ports and output ports via the switching device  120 . 
         [0022]    It is noted at this point that additional functional devices may be added to the functional devices  50  through  110  illustrated by way of example. Depending on the configuration of the switching device  120 , one or more functional devices may be interconnected, and connected between a selected input port and output port in order to map received input process data onto output process data according to a predetermined overall function. 
         [0023]    The connection device  40  may be configured with regard to the connection of the input ports to output ports and the corresponding interconnection of functional devices via the higher-order control device  20  or some other external device. The configuration parameters, such as the port number of the particular input ports and output ports and an identification of the functional devices to be connected in between, may be stored in the connection device  40  in the form of a look-up table. The switching device  120  may access the look-up table in order to establish the appropriate connections. 
         [0024]    Due to the invention, it is possible to more quickly transmit output process data to a destination actuator. This is because the input process data provided by the sensors now no longer have to be transmitted to the higher-order control device  20  via the connection device  40  and mapped onto output process data there. Instead, the input process data are processed directly in the connection device  40  itself, and then cyclically transmitted as output process data to a destination actuator. 
         [0025]    However, the input and output process data may still be monitored and observed by the higher-order control device  20 . In addition, the higher-order control device may communicate acyclically with the field devices in a conventional manner, as is necessary, for example, in the case of diagnostics or malfunctions.