Input / output station for a fieldbus system, fieldbus coupler for the input / output station, and placeholder module for the input / output station

Description

[0001] The present invention relates to an input / output station for a fieldbus system, which can be used, for example, for data acquisition and for controlling machines and systems, as well as a correspondingly designed fieldbus coupler and a corresponding placeholder module for the input / output station.

[0002] Communication systems of this type, such as input / output (I / O) stations, are frequently used in production facilities because their modular design allows for a wide range of applications within the production process. A communication system of this type typically includes a processor, a configuration memory, one or more pluggable input and / or output modules (I / O modules), and an internal bus system. The I / O module(s) form an interface through which process and control data, such as sensor and actuator signals, can be sent to and received from the devices being controlled. The bus system comprises, for example, a system bus with a data bus and a memory address bus for process data exchange between the processor and the I / O module, a control bus, and an address bus also known as a peripheral selection bus.Each I / O module has a unique address by which it can be selected via the address bus. A communication system of this type is known, for example, from EP 0 952 523 A1.

[0003] In another embodiment, the communication system includes a bus coupler and an internal bus system with integrated bus participants, as described in EP 2 274 655 A1. The bus participants are, in particular, I / O modules.

[0004] I / O stations can be configured in various ways. These include, firstly, a fully configured station, meaning the largest configuration where all slots are populated with functional I / O modules, and secondly, I / O station variants where one or more functional I / O modules are missing, leaving some slots empty. The order and type of I / O modules used are identical across all configurations.

[0005] For these different configurations of an I / O station, current best practices require that a separate project or sub-project be created in the engineering software for each configuration to ensure that the target configuration matches the actual configuration. When the I / O station is expanded with one or more additional I / O modules, the engineering software is then supplemented with another project containing the corresponding functionality.

[0006] This entails considerable effort for an I / O station already installed in a production plant section or machine, which can lead to lengthy downtimes. Furthermore, expanding a system carries technical risks, as signal propagation times can change as a result of the expansion. This leads to high conversion costs along with a difficult-to-calculate technical risk.

[0007] From EP 2 042 952 A1, a communication system of this type, designated as a switchgear control system, is known. It comprises a processor, a memory for current configurations, and at least one switchgear communication interface. The switchgear control system is capable of identifying a peripheral address as unpopulated and storing it in the memory for current configurations, reserving the address for the unpopulated device. To avoid an empty slot, a physical placeholder module can be used. This module occupies the slot in place of a functional I / O module and is assigned the address of the unused I / O module.

[0008] WO 2007 / 121968 A2 discloses a plug-in module for a communication interface in the fieldbus area, which incorporates a function of a programmable logic controller (PLC). The communication interface has an internal control function that acts on communication data as if the control function were implemented in another device.

[0009] Document WO 2007 / 149688 A2 relates to the configuration of modular distributed input / output (I / O) systems. The described I / O system enables the user to maintain a consistent I / O display in a distributed I / O network for various physically distributed I / O configurations where one or more I / O modules are physically removed from the system.

[0010] One of the aims of the invention is to reduce the design effort for a communication system of the type mentioned above.

[0011] This task is solved by an input / output station for a fieldbus system according to claim 1, a fieldbus coupler for an input / output station according to claim 10 and a placeholder module for an input / output station according to claim 11.

[0012] The dependent claims include advantageous further developments and improvements of the invention in accordance with the following description of these measures.

[0013] In one embodiment, the invention relates to an input / output station for a fieldbus system with a fieldbus coupler comprising a system bus interface and a fieldbus interface with corresponding firmware. The input / output station has a number of slots for pluggable input / output modules, into which, in addition to a number of input / output modules, at least one placeholder module is inserted. A special feature is that the fieldbus coupler includes firmware designed for a full configuration of the input / output station. The firmware is designed for communication with a control station such that it receives the full configuration of the input / output station from the control station as the planned target configuration. Furthermore, in one operating mode, the firmware confirms the full configuration of the input / output station, regardless of the actual configuration of input / output modules installed in the input / output station by the control station.This solution has the advantage that, for the various configurations of an input / output station, a separate project (i.e., more than one project) no longer needs to be created in the engineering software for each station configuration to ensure that the target configuration matches the actual configuration. This means that only one project needs to be created in the engineering software for the different configurations of an input / output station, thus reducing the engineering and administrative effort for the customer, i.e., the machine or plant manufacturer.

[0014] The control program also benefits. An optional expansion of a machine or plant component, such as in a production plant, can be planned for right from the initial commissioning of the control program. If an expansion is then to be integrated into the production plant, only the corresponding control section needs to be enabled for use in the control program, and the placeholder modules need to be replaced with the functional I / O modules intended for this purpose.

[0015] An extension of the solution involves designing the firmware so that the operating mode can be enabled and disabled upon confirmation of the fully configured input / output station via a parameter defined in the firmware. This parameter can be remotely set or removed by engineering software running on an engineering computer. This firmware design ensures backward compatibility, allowing the firmware to revert to the behavior of the previous firmware when the additional operating mode is disabled by setting the parameter accordingly.

[0016] It is also advantageous if, during a communication cycle with the control station, dummy data for at least one placeholder module is inserted or received from the control station. This has the advantage that the bus functionality of the fully expanded version is simulated, and replacing a placeholder module does not change the bus cycle times on the fieldbus. With the intelligent placeholder module, the cycle time of the system bus would even remain constant, since the placeholder module has the same process data width as the module that would otherwise be installed in the respective slot.

[0017] Another advantageous measure is that a placeholder module has a pre-configured memory in which a default configuration with a preset for the placeholder module is stored.

[0018] For internal communication within the input / output station, it is advantageous if the fieldbus coupler's firmware, in full configuration mode, communicates with the input / output modules of the station via the system bus using a reduced process data width. This reduction corresponds to the amount of data allocated per communication cycle for the unused input / output modules. The fieldbus coupler communicates with the input / output modules via the system bus of the station using this reduced process data width because the process data width of the actual configuration is less than the process data width of the target configuration. This applies to an unused slot or a slot containing a placeholder module with a process data width of 0.

[0019] In another variant, where the fieldbus coupler's firmware, operating in full-expansion mode, communicates with the input / output station's I / O modules via the system bus in full process data width, it is necessary to insert so-called intelligent placeholder modules into the empty slots. For such a placeholder module, it is advantageous that the intelligent placeholder module is designed to transmit simulated process data to and from the fieldbus coupler via the system bus for each internal communication cycle. This has the significant advantage that, even during the planned initial installation without fully populating the I / O station, the timing on the system bus corresponds to the timing of the fully expanded I / O station.

[0020] In another variant, it is advantageous for the firmware of the fieldbus coupler to be designed such that, during a communication cycle for data exchange with the control station, it inserts dummy data for the at least one plugged-in placeholder module and / or receives dummy data for the at least one placeholder module (37-39) from the control station (100). This also offers timing advantages. In this case, however, the timing on the fieldbus during communication with the control station, which can be implemented, for example, as a PLC (programmable logic controller), is crucial. The fieldbus timing is then maintained even during the planned initial installation without fully populating the input / output station and does not change with subsequent full configuration.

[0021] In a particularly simple variant, the fieldbus coupler for a configured analog output module, which is replaced by a placeholder module, receives dummy data (zeros) for the corresponding placeholder module from the control station but does not forward this data to the placeholder module via the system bus of the input / output station. The same can be done for an empty slot in the input / output station if no placeholder module is installed.

[0022] Similarly, it is advantageous that the fieldbus coupler sends dummy data (zeros) to the control station for a configured analog input module that has been replaced by a placeholder module. This ensures that the bus functionality is maintained and does not change when the placeholder module is replaced by a functioning input / output module. The same can be done for an empty slot in the input / output station when no placeholder module is installed.

[0023] The corresponding advantageous measures can be achieved for appropriately designed fieldbus couplers. In a first embodiment, the invention consists of a fieldbus coupler that includes firmware designed for a full configuration of the input / output station, wherein the firmware is designed for communication with a control station such that it receives the full configuration of the input / output station from the control station as the projected target configuration, and that the firmware, in an operating mode, confirms the full configuration of the input / output station regardless of the actual configuration of input / output modules of the control station.

[0024] Another embodiment of the invention consists of a placeholder module for an input / output station, characterized in that the at least one inserted placeholder module has at least one non-volatile memory and optionally a microcontroller, and it is ensured that either the memory or the microcontroller is designed to send the simulated process data to the fieldbus coupler via the system bus and to receive simulated process data from the fieldbus coupler.

[0025] Several embodiments of the invention are explained in more detail below with reference to the figures shown in the drawings.

[0026] They show: Fig. 1 a system overview of a machine or plant control system with a fieldbus system according to the prior art; Fig. 2 an input / output station of a fieldbus system according to the prior art; Fig. 3 a first preferred embodiment of an input / output station of the fieldbus system according to the invention; Fig. 4 a second preferred embodiment of an input / output station of the fieldbus system according to the invention; and Fig. 5 a flowchart illustrating the interaction of the firmware in the fieldbus coupler (21, 41) with the engineering software.

[0027] The present description illustrates the principles of the disclosure according to the invention. It is therefore understood that those skilled in the art will be able to conceive various embodiments which, although not explicitly described here, embody principles of the disclosure according to the invention and which are also intended to be protected in their scope.

[0028] Fig. 1This diagram shows a system overview for a machine or plant control system based on a fieldbus system. The fieldbus is designated by reference number 80. It is connected to the machine or plant control unit 100. This control unit 100 is typically located in the production hall. It corresponds to an industrial PC, often a PLC (programmable logic controller). The control programs are transmitted to the control unit 100 via another network 150, which can be, for example, an Ethernet network, particularly an Industrial Ethernet network. The development of the control programs, which are executed by the control unit 100, typically takes place away from the production hall in an office complex. Reference number 200 designates a project planning computer. The software engineer uses this project planning computer 200 to develop the control programs.The completed control programs are transmitted to the controller 100 via network 150. Various process or plant data are transmitted to the controller 100 via fieldbus 80. Conversely, the controller 100 transmits various control data to the corresponding machine or plant components. Input / output stations 10 are connected to fieldbus 80 for this purpose. These stations are equipped with a fieldbus coupler and various input / output modules, to which the various sensors S1, S2, and actuators A1 are connected. Fig. 1 A separate input / output unit 60 is also shown, which is not modular. A sensor S3 and an actuator A2 are connected to this unit. A switching unit 70 is also connected to it, to which further actuators A3 and A4 are connected.

[0029] The Fig. 2Figure 10 schematically depicts the state-of-the-art input / output station 10, which in its fully expanded configuration comprises six pluggable input and / or output modules (I / O modules) 1-6 and a fieldbus coupler 11. The fieldbus coupler 11 includes a fieldbus interface 14 and a system bus interface 12, which is connected to the internal system bus 16. The various I / O modules 1-6 are also connected to the system bus 16.

[0030] Each of the I / O modules 1-6 forms an interface through which process, machine, or plant data, such as sensor data, can be received and control data can be sent to devices to be controlled, such as actuators. Each I / O module 1-6 has a unique address, which allows it to be selected from system bus interface 22 via system bus 16 for sending output data and receiving input data.

[0031] If further functions are to be integrated into input / output station 10, additional I / O modules must be installed in communication system 10 to incorporate the newly added sensor and actuator data into the input / output cycle of input / output station 10. The new I / O modules contain, for example, analog inputs and outputs or digital inputs and outputs with corresponding functions. If analog sensor signals are present, they are digitized and then transmitted as digital data. The addition of further I / O modules also requires that the control program of control station 100 be extended to include this functionality. This involves considerable effort, particularly in terms of project planning.

[0032] A preferred first embodiment of an input / output station 20 according to the invention is shown schematically in the Fig. 3The input / output station 20 contains a fieldbus coupler 21 with a fieldbus interface 24 and a system bus interface 22 for a system bus 26, via which the fieldbus interface 24 is connected to several I / O modules. In the exemplary embodiment of the Fig. 3 The input / output station 20 has a configuration with six functional I / O modules 31-36 and three non-functional placeholder modules 37-39, in which Fig. 2 designated as "Wild Card" modules (WC1 - WC3). Each of the placeholder modules 37-39 has at least one pre-configured memory 37a-39a and optionally a microcontroller, in which a default configuration is stored, and each of the placeholder modules 37-39 is connected to the system bus interface 22 via the internal system bus 26.

[0033] When designing the control program for control station 100, a full configuration of input / output station 20 with nine functional I / O modules 31-39 is planned from the outset. The control program then also includes the corresponding program sections for the functional I / O modules, which are, however, still occupied by placeholder modules.

[0034] The input / output station 20 with its six I / O modules 31-36 is, for example, capable of controlling a machine or plant section. If this machine or plant section is to be expanded at a later date, one, two, or all three of the placeholder modules 37-39 are replaced by functional I / O modules, such as DI16, DO8, and AI4. The abbreviations DI stand for "Digital In," DO for "Digital Out," and AI for "Analog In." Since these functions essentially involve reading and outputting digital data or analog signals, they can be configured with the corresponding default settings so that the bus functionalities remain unchanged after the replacement with functional modules.This can be achieved in particular by the fieldbus coupler 21 and the fieldbus coupler in the control station 100 already assuming the full expansion of the input / output station 100 during the transmission cycles and inserting simulated input / output data for the placeholder modules 37 - 39.

[0035] Even during the initial planning phase with the Project Planning Computer 200, the system is designed for full configuration. The planning program only contains one project and is therefore already configured for all possible configurations, from a minimal configuration with one I / O module to a full configuration with nine I / O modules. Therefore, no changes to the planning program are necessary when commissioning a new configuration.

[0036] Placeholder modules 37-39 are equipped with at least one pre-configured memory and optionally a microcontroller. For example, the memory is already configured with a specific default configuration during manufacturing. A default configuration describes, in particular, the functionality of an I / O module that is intended to replace the corresponding placeholder module 37, 38, or 39 at a later date. The control program, which is executed in control station 100 for input / output station 20, is specifically designed for a full configuration with nine functional I / O modules, as the control program already includes the input / output functionalities of modules DI16, DO8, and AI4.If one or more of the placeholder modules 37-39 are later replaced by a corresponding I / O module provided for this purpose, the control program recognizes this because different input data than the simulated data of the default configuration is now supplied and automatically puts it into operation.

[0037] The placeholder modules 37-39 each contain, in particular, the same bus functionalities as the functional I / O modules to be used at a later time, in this embodiment the I / O modules DI16, DO8 and AI4. Thus, a later upgrade by adding planned optional machine or plant components does not change the system runtime if the control program is executed via the communication system 20.

[0038] In another preferred embodiment of the invention, in which Fig. 4In schematic representation, an input / output station 40 contains a system bus interface 42, a fieldbus coupler 44, and an internal bus system 46 (system bus), as well as four slots 51-54 for I / O modules. Each of the four slots 51-54 has a connector 51a-54a, via which an inserted I / O module is connected to the internal bus system 46.

[0039] The firmware for the 41 bus coupler is designed for a full configuration with four functional I / O modules, whereby the following four I / O modules can be used: digital input module, digital output module, analog input module, or analog output module. Permissible configurations for the four slots 51-54 are: 1.) Digital input module, digital output module, analog input module, analog output module, corresponding to a full configuration. 2.) Digital input module, digital output module, analog input module, placeholder module. 3.) Digital input module, digital output module, placeholder module, analog output module. 4.) Digital input module, digital output module, placeholder module, placeholder module, corresponding to a minimum configuration.

[0040] The following describes the behavior of the fieldbus coupler's firmware using the flowchart in Fig. 5This is explained. The firmware is designed for several variants. In step P1, the engineering software, running on the engineering computer 200, sends a target configuration to the control station 100 for preparation. This station forwards the target specification to the input / output stations 20 and 40. The fully expanded input / output station 40 is specified as the target configuration. This also occurs if the machine or plant manufacturer uses an input / output station 20 or 40 in their project that is not fully populated with input / output modules 31-39. This is because the machine or plant manufacturer only needs to create one project for all variants, thus reducing the engineering and administrative effort for the machine or plant manufacturer. In step S1, the target configuration specification is sent to the fieldbus coupler 21 or 41.The firmware of the fieldbus coupler 21, 41 then checks whether the specified target configuration is actually present in the input / output station 20, 40. First, in step S2, it is checked whether the input / output modules 31-39 configured by the target configuration are plugged into the designated location in the input / output station 20, 40. This corresponds to a typical process in the firmware of bus couplers for input / output stations 20, 40. The check is based on the assumption that functional input / output modules 31-36 are assigned an identification, which is queried in this step. The target configuration lists the identifications of the input / output modules 31-39 that are plugged in when fully configured.If this check detects that a different input / output module than the configured modules is plugged in, or that a configured module is plugged into a different slot than the intended one, an error message is returned to control station 100 in step S3. This message is then forwarded to the configuration computer 200. Simultaneously, an error indicator lamp can be illuminated at input / output stations 20 and 40. If input / output station 40 is equipped with an alphanumeric / graphic display unit, the error message can also be displayed there in text form.

[0041] If no incorrect assignment is detected, step S4 checks whether a placeholder module 37-39 is inserted in input / output station 20, 40, or alternatively, whether an unused slot is present. For the latter case, however, input / output station 20, 40 must be designed so that the fieldbus coupler 21, 41 recognizes that a slot 51a-54a is unused. Currently, the detection of an empty slot is performed using the firmware of the fieldbus coupler. Alternatively, this can be achieved through simple circuit design measures. For this purpose, it is sufficient that one contact per slot is closed or opened when an input / output module 31-39 is inserted, with these contacts being monitored by the fieldbus coupler 21, 41.

[0042] If no empty slot or placeholder module is detected, the fieldbus coupler 21, 41 assumes that the full configuration is present and the firmware branches to step S5, in which a message confirming the full configuration is sent back to the control station 100. This is forwarded to the configuration computer 200, which executes the configuration program with all program parts for all input / output modules 31-39 according to the full configuration in step P2.

[0043] If the check in step S4 detects an empty slot 51a-54a or a placeholder module 37-39, a further check follows in step S6. This check verifies whether an intelligent placeholder module 37-39 is plugged into a slot 51a-54a. This can be identified by the query for the identification of the placeholder module 37-39. In this respect, an intelligent placeholder module 37-39 behaves like a functional input / output module 31-39. If no intelligent placeholder module is detected, a message confirming the complete installation is sent back to control station 100 in step S7. If an intelligent placeholder module is detected, a message confirming the complete installation is also sent back to control station 100 in step S8.In both cases, i.e., after steps S7 and S8, the firmware of the fieldbus coupler 21, 41 begins inserting dummy data into the communication cycle for communication with the control station. If no intelligent placeholder module 37-39 is plugged in, i.e., after step S8, fixed data such as zeros can be inserted as process data in one variant. In another, improved variant, which is possible with intelligent placeholder modules, coded dummy data is inserted. This data allows, for example, the type of intelligent placeholder module 37-39 to be identified in the engineering software.

[0044] Steps S1 to S8 show the behavior of the firmware on the side of the fieldbus coupler 21, 41. Further steps follow on the side of the engineering software running on the engineering computer 200, which are also described in Fig. 5The following are shown. In step P3, it is checked whether coded dummy data is entered in the communication cycle for communication with control station 100. If so, this data is evaluated in step P3. This allows the engineering software to recognize intelligent placeholder modules 37-39 without having to send a request to input / output stations 20 and 40 itself. If the information about the installed placeholder modules 37-39 has been obtained in this way, the engineering software can decide which program parts must be omitted for the uninstalled input / output modules. If no intelligent placeholder module is installed, this information is obtained in step P4 by sending a conventional query of the current configuration to input / output stations 20 and 40.Upon receipt of the report on the current configuration, the corresponding program parts for the slots 31-39 that are not occupied by functional input / output modules can also be suppressed.

[0045] The placeholder modules for the input / output station 40 preferably have a process data width of zero bytes. If, for example, the input / output station 40 has configuration 4.) with two placeholder modules, the system bus interface 42 communicates with the available I / O modules with a reduced process data width during the execution of the control program in the control station 100, since the process data width of the actual configuration is smaller than the process data width of the full configuration.

[0046] For the planned analog output module, in whose slot one of the placeholder modules is still inserted, dummy data is sent to the fieldbus coupler 41. The fieldbus coupler 41 removes the process data for the analog output module, since this module is not installed or inserted behind the fieldbus coupler 41, but rather the placeholder module with a process data width of zero. For the planned but not installed or inserted analog input module, the fieldbus coupler 41 sends dummy data to the control station 100; however, since the program section for the analog input module is not executed there, the dummy data is recognized and not forwarded to the program section for this I / O module. The type of dummy data used for this purpose can be configured very flexibly. In the simplest case, "zeros" can be sent as dummy data.

[0047] For I / O stations with IP20 protection, where the I / O modules are plugged into slots in a base unit, unused slots must be covered to protect against ESD, dust, etc. This protection is provided when a placeholder module is inserted. However, it is not provided for exposed empty slots. To prevent this, a slot cover can be used. The absence of such a cover may go unnoticed and can lead to malfunctions or failure of the I / O station during operation, which in turn can result in machine or system downtime. Therefore, a solution is needed that automatically detects and displays the absence of this cover.

[0048] One solution relies on the cover incorporating electronics that allow it to be identified as such. An embodiment of this solution consists of an input / output station 10 comprising a fieldbus coupler 21, 41 and a base carrier with a number of slots 51a to 54a for I / O modules 31 to 39. Like the placeholder module with zero process data width, the slot cover is equipped with non-volatile memory, which is, for example, an EEPROM. This configuration is configured in project planning or engineering software using the corresponding device description files (e.g., GSDML for PROFINET). A corresponding device description file also exists for this type of slot cover. If the cover is missing, the project planning or engineering software displays a corresponding error message or warning.

[0049] The EEPROM can be programmed with a unique object with an ID code, e.g., a device type code. This programmed device type code can be evaluated by the fieldbus coupler 21, 41 of the input / output station 10. If the EEPROM is missing or the object with the device type code is missing, a warning is issued, e.g., "Slot not covered" or "ESD protection not inserted - Backplane x Slot y," including information about the affected slot (e.g., Backplane 3 Slot 5).

[0050] It should be understood that the proposed communication system can be implemented in various forms of hardware, software, firmware, and with specialized processors or a combination thereof. In a preferred embodiment, microcontrollers with integrated RAM and corresponding I / O interfaces are used for processors 22 and 42. Non-volatile, programmable memory is used for memories 37a-39a. Memories 24 and 44 can be volatile or non-volatile and may already be integrated into processors 22 and 42, respectively. Processors 22 and 42 can also include application-specific integrated circuits (ASICs), reduced instruction set computers (RISCs), and / or field-programmable gate arrays (FPGAs). Preferably, the proposed communication system is implemented as a combination of hardware and software.The software is preferably installed as an operating program on one or more non-volatile memory locations within the communication system 20 or 40.

[0051] The disclosure is not limited to the embodiments described here. There is scope for various adaptations and modifications that a person skilled in the art would consider based on their expertise and in relation to the disclosure itself. Reference symbol list Plug-in input / output modules 1-6 First input / output station 10 First fieldbus coupler 11 First system bus interface 12 First fieldbus interface 14 First system bus 16 Second input / output station 20 Second system bus interface 22 Second fieldbus coupler 21 Second fieldbus interface 24 Second system bus 26 Second pluggable input / output modules 31 - 36 Placeholder modules 37 - 39 Third Input / Output Station 40 Third system bus interface 42 Third fieldbus coupler 41 Third fieldbus interface 44 Third system bus 46 slots 51 - 54 Plug connections 51a - 54a Input / Output Unit 60 Switching unit 70 Fieldbus 80 Control station 100 network 150 Project computer 200 1. Sensor S1 2. Sensor S2 3. Sensor S3 1. Actuator A1 2. Actuator A2 3. Actuator A3 4. Actuator A4 Various steps in the project planning program P1 - P5 Various steps of the fieldbus coupler firmware S1 - S8

Claims

1. An input / output, I / O, station (20; 40) for a fieldbus system with a fieldbus coupler (21, 41), which has a system bus interface (22; 42) to a system bus (26, 46) and a fieldbus interface (24; 44), wherein the I / O station (20, 40) has a number of slots (51a-54a) to the system bus (26, 46) for pluggable I / O modules (31-36), into which, besides a number of I / O modules (31-36), also one or more placeholder modules (37-39) can be plugged, wherein an empty slot also represents a permissible variant, wherein the fieldbus coupler (21, 41) includes firmware that is designed for a full expansion of the I / O station (20, 40), wherein the firmware for communication with a control station (100) is designed such that it receives from the control station (100), as a projected target configuration, the full expansion of the I / O station (20; 40), characterized in that, in an operating mode, the firmware confirms to the control station (100) the full expansion of the I / O station (20; 40) irrespective of the actually present occupancy of the I / O station (20, 40) with I / O modules.

2. The I / O station (20; 40) according to claim 1, wherein the firmware is designed such that the operating mode with confirmation of the full expansion of the I / O station (20, 40) can be switched on and off via a parameter stored in the firmware, which can be remotely set or removed by an engineering software running on an engineering computer (200).

3. The I / O station (20; 40) according to claim 1 or 2, wherein the firmware of the fieldbus coupler (21, 41), in the operating mode with confirmation of the full expansion, communicates with the I / O modules (31-36) of the I / O station (20, 40) via the system bus (26, 46) with a reduced process data width, wherein the reduction of the process data width corresponds to the number of data that are planned per communication cycle for the unoccupied I / O modules (31-36).

4. The I / O station (20; 40) according to claim 1 or 2, wherein the firmware of the fieldbus coupler (21, 41), in the operating mode with confirmation of the full expansion, communicates with the I / O modules (31-36) of the I / O station (20, 40) via the system bus (26, 46) in full process data width, wherein at least one plugged-in placeholder module (37-39) of the one or the several placeholder modules (37-39) is designed such that it transmits simulated process data via the system bus (26, 46) to the fieldbus coupler (21, 41) per internal communication cycle and receives simulated process data from the fieldbus coupler (21, 41).

5. The I / O station (20; 40) according to claim 4, wherein the firmware of the fieldbus coupler (21, 41) is designed such that, in a communication cycle with the control station (100), it inserts the dummy data for the at least one plugged-in placeholder module (37-39) of the one or the several placeholder modules (37-39) and / or receives dummy data for the at least one placeholder module (37-39) of the one or the several placeholder modules (37-39) from the control station (100).

6. The I / O station (20; 40) according to claim 5, wherein the firmware is designed such that, as dummy data, it inserts a placeholder module type code for the at least one plugged-in placeholder module (37-39) of the one or the several placeholder modules (37-39) in the communication cycle with the control station (100).

7. The I / O station (20; 40) according to claim 4 or 5, wherein the firmware of the fieldbus coupler (21, 41) is designed such that, for a projected analog output module that is replaced by a placeholder module (37-39), it receives dummy data for the corresponding placeholder module (37-39) from the control station (100), but does not forward these via the system bus (26, 46) to the placeholder module (37-39).

8. The I / O station (20; 40) according to one of claims 4, 5 or 7, wherein the firmware of the fieldbus coupler (21, 41), for a projected analog input module that is replaced by a placeholder module (37-39), sends dummy data for the placeholder module (37-39) to the control station (100).

9. The I / O station (20; 40) according to one of claims 4 to 6, wherein the at least one plugged-in placeholder module (37-39) has at least one non-volatile memory and optionally a microcontroller, and which are designed to send simulated process data via the system bus (26, 46) to the fieldbus coupler (21, 41) and to receive simulated process data from the fieldbus coupler (21, 41).

10. A fieldbus coupler (21, 41) for an I / O station (20, 40) according to one of the preceding claims, characterized in that the fieldbus coupler (21, 41) is equipped with firmware according to one of the preceding claims.

11. A placeholder module (37-39) for an I / O station (20, 40) according to one of the preceding claims, characterized in that the placeholder module (37-39) has at least one non-volatile memory and optionally a microcontroller, which are designed to send simulated process data via the system bus (26, 46) to the fieldbus coupler (21, 41) and to receive simulated process data from the fieldbus coupler (21, 41).