Abstract:
Meeting the safety requirements of automation systems in a more flexible manner, the invention provides a control and data transmission system for controlling safety-critical processes, comprising a plurality of I/O modules connected via a first communication network to a gateway module. The gateway module is connected to a second communication network hierarchically superior to the first communication network and acts as a gateway between the first and the second communication networks. At least one of the I/O modules comprises a diagnosis unit for generating status data relating to the functional state of an input and/or output and/or of a process device. The gateway module and the I/O modules communicate via the first communication network in a safe manner to transfer status data and input and/or output data. The gateway module performs safety processing of the status data and/or of the input and/or output data.

Description:
FIELD 
       [0001]    The present invention generally relates to automation technology and, more particularly, to a control and data transmission system for controlling safety-critical processes involving a plurality of input and/or output modules which are connected to a gateway module via a communication network, and also relates to a method for a safe process control. 
       BACKGROUND 
       [0002]    In automation technology, process control is often accomplished using a control unit that is connected, via a communication system, to decentralized input and output modules, or I/O modules for short. The connection to the process to be controlled is effected by sensors and actuators which are connected to respective I/O modules, the I/O modules receiving input data from sensors and outputting output data to actuators. 
         [0003]    The communication system may be a field bus system, for example. It is likewise possible that a hierarchical communication structure is provided, in which case different communication networks can be interconnected by a gateway module. For example, it is known to use modular stations which comprise a bus coupler and a plurality of I/O modules, for example in the form of electronic plug-on modules, and in this case the communication between the bus coupler and the I/O modules is usually effected via a local bus, and the bus coupler has an interface to a higher level fieldbus. The connection within the local bus can be made by means of contacts without cables, and for this purpose the bus coupler and the I/O modules are snap-connected onto a mounting rail, in particular a DIN hat rail. A gateway module which comprises the bus coupler and which connects the local bus to a hierarchically superior communication network is also referred to as a bus terminal in this context. 
         [0004]    It is often necessary to implement safety functions for the protection of humans, machines, or the environment, for example shut-down of a machine after a protective door has been opened or an emergency stop switch has been actuated. The input and output data which are processed and/or generated by safety functions and which are therefore relevant to safety are usually processed by safe I/O modules and are exchanged between a control unit and the I/O modules using a safe transfer protocol. 
         [0005]    Known standards for the development of electrical, electronic and programmable electronic systems that perform a safety function are IEC 61508 and ISO 13849, for example. 
         [0006]    Currently, special safe input and output modules are used for the acquisition of safety-relevant signals, which modules gather the signals redundantly and check them for plausibility and errors within the device. For this purpose, at least two cores or channels are necessary, which are typically implemented by means of microprocessors which process the acquired data in two channels and compare them with one another. Subsequently, safe communication is implemented separately in each module. Modular stations comprising a plurality of modules usually use safe input and output modules which operate independently of one another and are individually addressed by the higher level control unit. 
         [0007]    In addition, the modular stations usually also include modules for the acquisition of signals that are not safety-relevant, which modules are typically configured with a single channel, and further comprise at least one gateway module for coupling the station to the respective higher level network that is used. The gateway module disclosed herein is also a smart device, insofar as it adapts to the network and accordingly converts the data from the local I/O modules. 
         [0008]    Thus, different I/O modules are employed for safety-relevant and non-safety-relevant signals. This increases the efforts involved in development, manufacturing, logistics, training and all aspects related to automation. Moreover, the number of cores implemented with microprocessors within such a station increases with each further module, making them technically and commercially more complex. In addition, depending on the network employed, a different safety protocol has to be implemented for the transfer of the safety-relevant signals. This further increases the variety of the modules. 
         [0009]    The invention is based on the objective of providing a way in which safety requirements imposed on an automation system can be met in an improved, optimized or more flexible in nature compared to prior disclosures. 
         [0010]    The aforementioned technical objective is achieved through the present invention. 
       SUMMARY 
       [0011]    Accordingly, embodiments of the invention provide a control and data transmission system for controlling safety-critical processes. The invention, at least, comprises a plurality of I/O modules that are connected via a first communication network to a gateway module and wherein the gateway module is connected to a second communication network hierarchically superior to the first communication network and acts as a gateway between the first and the second communication network. At least one of the I/O modules comprises a diagnosis unit for generating status data relating to the functional state of an input and/or output and/or of a process device connected to an input or output. Furthermore, the gateway module and the I/O modules are adapted to communicate via the first communication network in a safe manner to transmit status data and input and/or output data. The gateway module is furthermore adapted to perform safety-related processing of the status data and/or of the input and/or output data. 
         [0012]    Advantageously, the safety-related processing of the status data and/or of the input and/or output data by the gateway module may additionally comprise the execution of at least one safety function. In this case, preferably, the safety function generates safety-related output data on the basis of safety-related input data and on the basis of the transferred status data. A safety function may as well include a safe association which is used for safety-related association of redundantly provided signals or data, for example. 
         [0013]    The I/O modules may advantageously be configured as input and/or output modules, which means they have input and/or output terminals for connecting process devices such as sensors and/or actuators. 
         [0014]    The gateway module preferably processes the input data and the status data of the input modules in a manner so that the input data comply with the requirements of the safety standards. The safe input data can then be transmitted to a higher level safety control unit and/or to a higher level standard control unit. Additionally or alternatively, these data can be safely processed within the gateway module and the result can be supplied to the outputs. 
         [0015]    On the output side, the gateway module is preferably responsible for the transmission of the output data and the diagnosis of the output circuits, so that the state of the output modules is monitored in order to be able to react accordingly in the event of a fault. 
         [0016]    The outputs may, for example, be controlled so that two output modules are controlled which together define a safe two-channel output. However, it is also possible, for example, to use common outputs which are monitored, and only one upstream safe output module is provided which, in the event of a fault, switches off power supply to the common output modules. 
         [0017]    A key idea of the present invention is to shift the safety logic into the gateway module instead of providing it in the individual I/O modules, so that, advantageously, the acquisition of safety-relevant signals is made using I/O modules which usually are only configured for not safety-relevant signals, in particular with single-channel I/O modules. Since in terms of physics the general signals are the same in the case of safety-relevant I/O modules and not safety-relevant I/O modules it is in particular contemplated according to the invention to capture safety-related and not safety-related signals with identical I/O modules, whereby flexibility is increased since fewer different I/O modules need to be used. This allows development efforts to be significantly reduced as well. So, preferably, safety-relevant input data are also acquired by a single-channel input module and/or safety-relevant output data are output by a single-channel output module. 
         [0018]    In accordance with the invention, checking and cross-checking of data, which according to the prior art takes place in two-channel I/O modules for safety-relevant signals, is performed at a central location in the gateway module. For this purpose, the gateway module preferably comprises a safety logic having a redundant design and adapted for executing safety-related processing of status data and/or of input and/or output data and/or for executing a safety function. 
         [0019]    In a particularly advantageous embodiment of the control and data transmission system, the first communication network is a local bus, and the I/O modules are configured as modular input and output devices. The local bus preferably supports at least one selected bus protocol, for example a field bus protocol such as INTERBUS or Profibus. In principle, however, any suitable bus protocol can be used. Since the connection within the local bus is advantageously made without cables, by contacts that are snap-connected onto a mounting rail, the local extension within the station comprising the gateway module and the I/O modules is limited. It has been discovered that with this embodiment, a complete safety protocol as known from the prior art for the transfer of safety-related data is not required, rather sufficient safety can be ensured by a few technical measures against data corruption and irregularities in the data transfer. Safe communication is only necessary from the gateway module, also referred to as a bus terminal, to the second, higher level communication network. The second communication network may be configured as a field bus, for example. 
         [0020]    Process control is typically accomplished using a control unit that is connected to the second communication network, for example in the form of a programmable logic controller (PLC). Since the safety-related logic processing is performed by the gateway module, the gateway module is adapted for processing both safety-related and not safety-related data. It is moreover conceivable that the gateway module performs the process control for the local station, meaning that the complete control of the inputs and outputs of the I/O modules connected to the first communication network. 
         [0021]    As found, only a few diagnosis extensions are required in the I/O modules instead of the safety logic used according to the prior art for capturing the safety-related physical signals in a safe manner and transferring them to the gateway module in the present invention. These are used in particular for diagnosis of the transfer path from the I/O module to the gateway module and for diagnosis of the peripherals and the inputs and outputs. 
         [0022]    Accordingly, the gateway module and the I/O modules are adapted for safe communication. The modules are adapted for exchanging data telegrams for safe communication are particularly advantageous as they comprise a checksum and/or at least a counter value, and the counter value is incremented after each successfully transmitted data telegram. The checksum may be a Cyclic Redundancy Check (CRC), for example. By virtue of the dynamics, i.e. the change in the counter value, it is possible to detect errors in the data transfer, in particular lost or duplicated data telegrams. 
         [0023]    According to a particularly advantageous embodiment, it is furthermore contemplated that for each of the I/O modules connected to the first communication network the respective data telegram comprises a different, individual counter value. The use of individual counters which have respective different values in a data telegram for each of the I/O modules particularly advantageously enables a diagnosis of the addressing of the individual I/O modules within the station. Advantageously it may be contemplated that a common data telegram passes through all the I/O modules connected to the first communication network and comprises the respective individual counter values for the I/O modules. 
         [0024]    In contrast to the prior art, the individual I/O modules only use simple diagnosis instances which support the safety logic in the gateway module for fault detection. For this purpose, at least one I/O module, typically all I/O modules, has/have a diagnosis unit which is adapted for diagnosing the inputs and/or outputs of the respective I/O module and/or for diagnosing a process device connected to an input or output of the respective I/O module, and for generating corresponding status data. For example, a diagnosable fault of an input or output may be a short circuit to ground that occurred. 
         [0025]    For diagnosis of the peripherals, i.e. of a connected process device such as a sensor or actuator, it is advantageously contemplated that the diagnosis unit in the respective I/O module exchanges data with an associated diagnosis unit which is arranged in a process device connected to an input or output of the I/O module. In this way it is possible to detect and query faults in the peripheral device by the diagnosis unit in the I/O module. 
         [0026]    Particularly advantageously, the diagnosis unit of at least one I/O module and/or the diagnosis unit of a process device connected to the I/O module can be controlled by control data transmitted from the gateway module. For this purpose, different diagnosis instances may be provided within the diagnosis units in the I/O modules and/or in the connected peripheral devices, which are addressed by the safety logic located in the gateway module and are checked for faulty behavior by the expectations in the safety logic. Thus, the diagnosis units in the I/O module and/or in the process device are remote controlled by the gateway module. Therefore, separate protection and diagnosis evaluation in the I/O modules is not required. Processing of the I/O data and diagnosis data is exclusively executed in the gateway module. 
         [0027]    Further deficiencies in prior disclosures are also remedied by the described embodiments of the present invention. 
         [0028]    Accordingly, a gateway module is provided for use in the described control and data transmission system, which gateway module comprises interfaces for connection to a first and a second communication network, the gateway module being connectable to a plurality of I/O modules via the first communication network, and the gateway module being adapted to communicate with the I/O modules via the first communication network in a safe manner to transmit input and/or output data and to receive status data from at least one I/O module. Furthermore, the gateway module comprises a safety control unit in particular in the form of a safety logic which is adapted for executing safety processing, i.e. safety-related processing, of the status data and/or of the input and/or output data. 
         [0029]    On the basis of the safety-related processing in the gateway module, safety functions may advantageously be executed in a higher level safety control unit. However, according to an advantageous embodiment it may also be contemplated that the gateway module is adapted to execute at least one safety function which preferably generates safety-related output data on the basis of safety-related input data and on the basis of received status data. In such an embodiment, advantageously, the execution of safety functions in a higher level safety control unit can be dispensed with, however it is likewise possible that additional safety functions are executed in a higher level safety control unit. 
         [0030]    Furthermore, all the embodiments of such a gateway module that have been described above in conjunction with the control and data transfer system are also within the scope of the invention. 
         [0031]    Accordingly, in another embodiment of the present invention, an I/O module for use in the described control and data transmission system is provided, which comprises at least one input and/or output for connecting a process device, in particular in the form of a sensor or actuator, a diagnosis unit for generating status data relating to the functional state of the input and/or output and/or of a process device connected to the input and/or output, and an interface for connection to a communication network, and the I/O module is adapted to communicate with a gateway module via the communication network in a safe or safety-related manner. 
         [0032]    Moreover, all the embodiments of such an I/O module that have been described above in conjunction with the control and data transmission system are also within the scope of the invention. 
         [0033]    Accordingly, a method is provided for a safe or safety related process control in a control and data transmission system which comprises a plurality of I/O modules, wherein the I/O modules are connected to a gateway module via a first communication network, and wherein the gateway module is connected to a second communication network hierarchically superior to the first communication network and acts as a gateway between the first and second communications network. The method comprises generating status data by a diagnosis unit located in at least one of the I/O modules, the status data comprising information relating to the functional state of an input and/or output of the I/O module and/or of a process device connected to the input and/or output of the I/O module, executing a safe communication between the gateway module and the I/O modules via the first communication network to transfer status data and input and/or output data, and safety-related processing of the status data and/or of the input and/or output data by the gateway module. 
         [0034]    The safety-related processing may advantageously comprise the execution of at least one safety function by the gateway module, in which case the safety function generates safety-related output data on the basis of safety-related input data and on the basis of status data. 
         [0035]    Preferably, the method comprises all the necessary method steps for operating the above-described embodiments of a control and data transmission system or combinations thereof. 
         [0036]    Furthermore, the method may advantageously be adapted for remote controlling, by the gateway module, a diagnosis unit arranged in one of the I/O modules, for which purpose control data are transmitted from the gateway module to the diagnosis unit. 
         [0037]    These and other advantages will be apparent from the present application of the embodiments described herein. 
         [0038]    The preceding is a simplified summary to provide an understanding of some embodiments of the present disclosure. This summary is neither an extensive nor exhaustive overview of the present disclosure and its various embodiments. The summary presents selected concepts of the embodiments of the present disclosure in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the present disclosure are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    The invention will now be described in more detail by way of preferred exemplary embodiments and with reference to the accompanying drawings. The foregoing and other aspects of the embodiments disclosed herein are best understood from the following detailed description when read in connection with the accompanying drawings. For purposes of illustrating the embodiments disclosed, the preferred embodiments are shown in the drawings. However, the embodiments disclosed herein are not limited to the specific instrumentalities disclosed. The same reference numerals in the drawings designate the same or equivalent parts. Included in the drawings are the following figures: 
           [0040]      FIG. 1  shows a schematic diagram of a control and data transmission system known from prior art; 
           [0041]      FIG. 2  shows a schematic diagram of a preferred embodiment of a control and data transmission system according to the invention; 
           [0042]      FIG. 3  schematically illustrates the data exchanged with an I/O module of the control and data transmission system shown in  FIG. 2 ; and 
           [0043]      FIG. 4  schematically illustrates a time profile of counter values of individual I/O modules which are transmitted within data telegrams. 
       
    
    
       [0044]    While embodiments of the present disclosure are described herein by way of example using several illustrative drawings, those skilled in the art will recognize the present disclosure is not limited to the embodiments or drawings described. It should be understood the drawings and the detailed description thereto are not intended to limit the present disclosure to the particular form disclosed, but to the contrary, the present disclosure is to cover all modification, equivalents, and alternatives falling within the spirit and scope of embodiments of the present disclosure as defined by the appended claims. 
         [0045]    The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures. 
       DETAILED DESCRIPTION 
       [0046]    Embodiments of the present disclosure will be described below in conjunction with exemplary control and data transmission systems, gateway modules, I/O modules, and methods for process control. Those skilled in the art will recognize the disclosed techniques may be used in building any railing that may be aesthetically pleasing. 
         [0047]    The phrases “at least one”, “one or more”, and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
         [0048]    The term “a” or “an” entity refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. 
         [0049]      FIG. 1  schematically shows a control and data transmission system  20  known from prior art, which comprises a plurality of I/O modules  40 ,  45 ,  50 , and  55 , each one connected, via a bus interface  70 , to a bus master  60  that is located in a gateway module  30 . Gateway module  30  further comprises a network coupler  90  for connection to a higher level network. Typically, a control unit (not shown in  FIG. 1 ) is connected to this higher level network, which individually addresses the I/O modules  40 ,  45 ,  50 , and  55 , which are operating independently from each other. I/O modules  40  and  50  are configured as input modules, and I/O modules  45  and  55  are configured as output modules. I/O modules  50  and  55  are configured as special safety I/O modules in which the signals are captured twice and checked within the device for plausibility and errors, and for this purpose two cores  80  and  81 , and  85  and  86 , respectively, are provided, which are implemented by microprocessors. 
         [0050]      FIG. 2  schematically illustrates a preferred embodiment of a control and data transmission system  10  according to the invention, in which the two-channel I/O modules known from prior art for capturing safety-relevant signals have been dispensed with. 
         [0051]    Control and data transmision system  10  comprises a gateway module  100 , and I/O modules  201  and  202  which are able to communicate with one another via a local bus  510 . In the illustrated exemplary embodiment, local bus  510  is configured as a ring bus, and for communication with the I/O modules  201  and  202 , local bus master  120  in the gateway module generates a data telegram which is passed through all the I/O modules connected to the bus  510 , in the manner of a shift register. For the sake of simplified illustration, only two I/O modules  201  and  202  are shown. However, a significantly greater number of I/O modules may be provided. The illustrated embodiment of the local bus  510  as a ring bus is merely by way of example, any other suitable bus topology may be used as well. Furthermore, a selected bus protocol is preferably used for communication via the local bus  510 , preferably a fieldbus protocol. However, in principle any suitable communication protocol can be used. 
         [0052]    According to the invention, the safety logic is shifted from the I/O modules into the gateway module  100 . This is symbolized in  FIG. 2  by the dashed arrows. The gateway module  100  accordingly comprises a safety control unit  130  which is connected to local bus master  120 . Advantageously, safety control unit  130  comprises two redundant cores  131  and  132  that are implemented by means of microprocessors, the results of which are compared with each other. Safety control unit  130  is in particular adapted to execute a safety function which generates safety-related output data on the basis of safety-related input data. 
         [0053]    The execution of the safety function by gateway module  100  additionally occurs on the basis of status data which are generated by diagnosis units  400  in the I/O modules and are transferred to the gateway module  100 . 
         [0054]    Communication between gateway module  100  and I/O modules  201  and  202  is effected in a safe manner, and for this purpose the I/O modules comprise a communication diagnosis unit  300  each of which is connected to a bus interface  210  via registers  220  and  225  for input and output data. Communication diagnosis unit  300  comprises a unit  310  configured for performing a safe communication. Advantageously, it may be contemplated for unit  310  to be provided in the form of a chip. Furthermore, the communication diagnosis unit  300  and the unit  310  for performing safety communication may be implemented in a common chip, optionally with registers  220  and  225  and/or with the bus interface  210 . Communication diagnosis unit  300  is connected to diagnosis unit  400  which is adapted for diagnosis of an input and/or output and/or of a process device connected to an input or an output and for generating corresponding status data. Advantageously, diagnosis unit  400  may also be configured as a chip, or may also be implemented on a common chip together with communication diagnosis unit  300 . 
         [0055]    In the illustrated exemplary embodiment, diagnosis unit  400  comprises a Serial Peripheral Interface (SPI) master  420  which is connected, via an I/O interface  410 , to an I/O unit  430  comprising the inputs and outputs and optionally provided timers. I/O interface  410  is connected to the unit  310  of communication diagnosis unit  300 . The inputs and/or outputs which are embodied as general purpose inputs/outputs (GP I/Os), for example, are connected to one or more process devices, i.e. to peripheral devices such as sensors or actuators, via interface  450 . Interface  450  may serve to perform signal adaptations or A/D conversion, for example. 
         [0056]    Gateway module  100  further comprises a network gateway  110  for connection to a higher level network  520 . In gateway module  100  the internal signals are translated to the network  520  which is employed. The safety protocol is adapted to the higher level network  520 , so that when the same physical interface is used the gateway module is only different in terms of the network protocols or is able to support a plurality of protocols. This makes it possible to use the same gateway module  100  for different networks and safety protocols. 
         [0057]    Therefore, the only thing that is required according to the invention for capturing the physical signals in a safe manner and transmitting them to the gateway module is a diagnosis of the transfer path from the I/O module to the gateway module and a diagnosis of the peripherals and of the inputs/outputs. 
         [0058]    In the illustrated exemplary embodiment, gateway module  100  and I/O modules  201  and  202  are configured as plug-on terminals whereby their local extent is limited so that a completely developed safety protocol is not required, but only a few technical measures against data corruption and irregularities in the data transfer. Safety communication is only necessary from the gateway module  100  into the higher level network  520 . 
         [0059]    Thus, all the I/O modules  201  and  202  are independent of which safety protocols are used in the higher level network  520 , and so they can have the same configuration. The safety logic in gateway module  100  ensures safety data communication to the individual I/O modules and serves the individual diagnosis instances within the I/O modules. 
         [0060]      FIG. 3  illustrates, in schematic and simplified manner, which data the exemplarily selected I/O module  201  receives from gateway module  100 , how these data are forwarded, and which data are returned to gateway module  100 . 
         [0061]    Safety communication between the safety logic of gateway module  100  and the I/O modules is ensured using a CRC. Additionally, each I/O module is preferably addressed with a counter of 8 bits, for example, which is different for each local I/O module and is incremented after each successful communication connection. The I/O module responds with a mirrored counter value. This counter value represents a diagnosis procedure for addressing the individual I/O modules. Due to the dynamics produced by the change in the counter value, also referred to as count for short, it is possible to detect further faults in the data transfer. 
         [0062]    As shown in  FIG. 4 , each I/O module is addressed with a different counter. After each successful communication connection, all counters are incremented, up to a maximum value. Once the maximum value has been reached, each counter is reset to an initial value. In this manner, the counter values, or counts, for individual I/O modules differ for each data transmission, for example at time t 0 . The continuous characteristics shown in  FIG. 4  only symbolically reflect the course of the discrete counter values. 
         [0063]    Referring back to  FIG. 3 , all the received data, including the count, output data, control data, and the CRC, are supplied to communication diagnosis unit  300  which checks the CRC and the count. The output data are directly output to the peripherals  600 . The control data are supplied to diagnosis unit  400  and serve to remotely control diagnosis unit  400 , i.e. for example, for defining which status data are to be provided by the diagnosis unit  400 . 
         [0064]    The data to be sent to the gateway module  100  include the mirrored count, input data, status data, and CRC. The input data provided by the peripherals and the status data generated by diagnosis unit  400  are supplied to communication diagnosis unit  300  for generating the CRC. For generating the status data, by diagnosis unit  400 , communication in particular takes place between diagnosis unit  400  and peripherals  600 . 
         [0065]    The execution of the communication (state machine) takes place exclusively in the safety logic of gateway module  100 . The individual I/O modules only use simple diagnosis instances which support the safety logic in the gateway module  100  in fault detection. 
         [0066]    Different diagnosis instances may be provided in diagnosis unit  400  as well as in peripherals  600 , which are addressed by the safety logic of the gateway module  100  and are checked for faulty behavior by the expectations in the safety logic. Separate safeguarding and evaluation of the diagnosis in the I/O modules is therefore no longer required. The processing of the I/O data and of the diagnosis data is done exclusively in the gateway module  100 . 
         [0067]    Since the gateway module  100  performs the logic processing and is able to process both standard data and safety-related data, it is furthermore disclosed that the gateway module  100  takes over complete control of the inputs and outputs of the local station, i.e. the local I/O modules. The gateway module  100  may be employed as a local controller in a stand-alone mode and, in addition, it provides the necessary data for the higher level network  520  or can be controlled as a local smart station. The processing in the gateway module has the advantage that it can be executed much faster than in a higher level control unit, because the local station has more efficient and faster access to the local I/O data. Thus, shorter response times can be achieved. In addition, the higher level control unit is relieved. 
         [0068]    The solution of the invention offers a number of advantages over the current prior art. A more flexible use of existing I/O modules for non-safety-relevant signals and a reduction in the number of different I/O modules within the system is achieved. In addition, all I/O modules can be configured independently of the higher level network. A simplification of the I/O modules moreover results because the latter need no longer be configured for safety capturing of the signals. Accordingly, few or no microprocessors are required within the station which includes the gateway module and the I/O modules, and overall complexity within the station is reduced. Furthermore, efforts in development, production, testing, and support are also reduced in this way. Moreover, depending on the local communication system, separate addressing of the modules for safety-related signals may also be omitted. 
         [0069]    Furthermore, only one logic processing is required in the system. The gateway module is moreover capable of completely fulfilling the safety tasks as a separate station without connection to the higher level network, that is to say, not only detection of the inputs and outputs but also control within the local station can be realized. Both the safety signals and the standard signals can be used. Processing of the local I/O data in the gateway module is much faster than in a higher level control unit. Furthermore, it is conceivable that the centralized safety processing is performed not exclusively in the gateway module, but also at a different location, such as e.g. in a higher level safety control unit, or anywhere within the local station, and that the gateway module only functions as a gateway. In this case, the gateway module provides the data transfer to the devices and various services that are necessary to control the diagnosis units and the I/O data of the individual local devices. 
         [0070]    Although the invention has been described with reference to exemplary embodiments, it is not limited thereto. Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the true spirit of the invention. It is therefore intended that the appended claims be construed to cover all such equivalent variations as fall within the true spirit and scope of the invention. 
         [0071]    The exemplary embodiments of this present invention have been described in relation to a railing system. However, to avoid unnecessarily obscuring the present invention, the preceding description omits a number of known structures and devices. This omission is not to be construed as a limitation of the scope of the present invention. Specific details are set forth by use of the embodiments to provide an understanding of the present invention. It should however be appreciated that the present invention may be practiced in a variety of ways beyond the specific embodiments set forth herein. 
         [0072]    A number of variations and modifications of the present invention can be used. It would be possible to provide for some features of the present invention without providing others. 
         [0073]    The present invention, in various embodiments, configurations, and aspects, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. Those of skill in the art will understand how to make and use the present invention after understanding the present disclosure. The present invention, in various embodiments, configurations, and aspects, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments, configurations, or aspects hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and/or reducing cost of implementation. 
         [0074]    The foregoing discussion of the present invention has been presented for purposes of illustration and description. It is not intended to limit the present invention to the form or forms disclosed herein. In the foregoing Detailed Description, for example, various features of the present invention are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the embodiments, configurations, or aspects may be combined in alternate embodiments, configurations, or aspects other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention the present invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the present invention. 
         [0075]    Moreover, though the description of the present invention has included description of one or more embodiments, configurations, or aspects and certain variations and modifications, other variations, combinations, and modifications are within the scope of the present invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights that include alternative embodiments, configurations, or aspects to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.