INTERFACE ARRANGEMENT FOR CONNECTING AT LEAST ONE CONTROL DEVICE TO A PLURALITY OF FIELD INSTRUMENTS

Abstract

An interface arrangement for connecting at least one control device to a plurality of field instruments, includes: a carrier board having a plurality of signal channels, and a connector designed for electrical and mechanical connection to a second, complementary connector of a signal processing device, being arranged between a first and a second connecting device of each signal channel. Each signal channel has an electrical interface which is designed for releasable connection of respective surge protection modules, each interface electrically connected to an electrical resistor and to a surge arrester which is arranged at least partially on and/or in the carrier board and is designed for arresting surge voltages and/or surge currents which may occur.

Claims

1. An interface arrangement for connecting at least one control device to a plurality of field instruments, comprising: a carrier board having a plurality of signal channels, each of which has a first connecting device and a second connecting device, the first connecting devices designed for connection of a respective field instrument and the second connecting devices designed for connection of at least one control device, a connector designed for electrical and mechanical connection to a respective second, complementary connector of a signal processing device, being arranged between the first and the second connecting device of each signal channel, each signal channel having an electrical interface which is designed for releasable connection of respective surge protection modules and being arranged on the carrier board between the respective connector and the respective first connecting device, each interface being connected to an electrical resistor, and a surge arrester electrically connected to the interfaces, which is arranged at least partially on and/or in the carrier board and is designed for arresting surge voltages and/or surge currents which may occur.

2. The interface arrangement according to claim 1, wherein the signal channels are arranged parallel to one another, in that each signal channel has at least one first signal line portion which electrically connects the first connecting device of the respective signal channel to the respective connector and into which the electrical resistor of the respective signal channel is connected, wherein each signal channel has at least one second signal line portion which electrically connects the second connecting device of the respective signal channel directly or indirectly to the respective connector, wherein the first connectors are arranged side by side on the carrier board, and wherein the surge arrester comprises an electrical conductor which runs at right angles to the first signal line portions.

3. The interface arrangement according to claim 2, further comprising: a ground connection, which is connected to the electrical conductor, is arranged on the carrier board.

4. An interface arrangement for connecting at least one control device to a plurality of field instruments, comprising: at least one first carrier board having a plurality of first signal channels, each of which has a first connecting device and a second connecting device, the first connecting devices designed for connection of a respective field instrument and the second connecting devices designed for electrical connection to third connecting devices of a second carrier board, each first signal channel having an electrical interface which is designed for connection of a surge protection module and being arranged between the first and the second connecting device of the respective signal channel, each interface being connected to an electrical resistor, a surge arrester electrically connected to the interfaces and arranged at least partially on and/or in the at least one first carrier board, the surge arrester designed for arresting surge voltages and/or surge currents which may occur, a second carrier board having a plurality of second signal channels, each of which has a third connecting device and a fourth connecting device, the fourth connecting devices designed for connection of at least one control device and at least some of the third connecting devices designed for electrical connection to the second connecting devices of the at least one first carrier board, wherein, when the at least one first carrier board and the second carrier board are coupled to one another, there is an electrical connection between the second connecting device and the respective third connecting devices, and a connector arranged between the third and the fourth connecting device of each second signal channel, the connectors designed for electrical and mechanical connection to a respective second, complementary connector of a signal processing device.

5. The interface arrangement according to claim 4, wherein the first signal channels of the at least one first carrier board are arranged parallel to one another, wherein each first signal channel has at least one first signal line portion which extends from the first connecting device of the respective first signal channel to the second connecting device and into which the electrical resistor of the respective signal channel is connected, and wherein the surge arrester has an electrical conductor which runs at right angles to the first signal line portions.

6. The interface arrangement according to claim 5, further comprising: a ground connection connected to the electrical conductor, the ground connection arranged on the at least one first carrier board.

7. The interface arrangement according to claim 4, further comprising: a further first carrier board having a plurality of third signal channels, each of which has a fifth connecting device and a sixth connecting device, the fifth connecting devices designed for connection of a respective field instrument and the sixth connecting devices designed for electrical connection to the remaining third connecting devices of the second carrier board, each third signal channel having an electrical interface which is designed for connection of respective surge protection modules and arranged between the fifth and the sixth connecting device of the respective third signal channel, each interface connected to an electrical resistor, and a surge arrester electrically connected to the interfaces the surge arrester arranged at least partially on and/or in the further first carrier board and designed for arresting surge voltages and/or surge currents which may occur.

8. The interface arrangement according to claim 4, wherein the second signal channels (280.sub.1-280.sub.n) are arranged parallel to one another, each second signal channel has at least one first signal line portion which electrically connects the third connecting device of the respective second signal channel to the respective connector, wherein each second signal channel has at least one second signal line portion which electrically connects the fourth connecting device of the respective second signal channel directly or indirectly to the respective connector, and wherein the connectors are arranged side by side on the carrier board.

9. The interface arrangement according to claim 4, wherein the interface arrangement is designed as a wiring and/or signal converting means.

10. The interface arrangement according to claim 4, wherein the interface arrangement is designed for mounting on a mounting rail.

11. The interface arrangement according to claim 4, wherein the interfaces are designed to accommodate surge protection modules designed as plug-in modules.

12. The interface arrangement according to claim 1, wherein the interface arrangement is designed as a wiring and/or signal converting means.

13. The interface arrangement according to claim 1, wherein the interface arrangement is designed for mounting on a mounting rail.

14. The interface arrangement according to claim 1, wherein the interfaces are designed to accommodate surge protection modules designed as plug-in modules.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is explained in more detail below with reference to two embodiments in conjunction with the accompanying drawings, in which:

[0022] FIG. 1 is a plan view of an exemplary interface arrangement according to the invention,

[0023] FIG. 2 is a cross-sectional view along the first signal channel of the interface arrangement shown in FIG. 1,

[0024] FIG. 3 is a plan view of an alternative exemplary interface arrangement according to the invention, and

[0025] FIG. 4 is a cross-sectional view along the first signal channel of the interface arrangement shown in FIG. 3.

DETAILED DESCRIPTION

[0026] It should be noted in advance that the index n used in the reference signs can be equal to 16, for example.

[0027] FIG. 1 shows an exemplary interface arrangement 10 which is designed for connecting a plurality of field instruments to at least one control device, with signals to and from the field instruments being sorted, processed and/or converted depending on the implementation. The field instruments can be sensors and/or actuators. The exemplary interface arrangement 10 comprises a carrier board 40 having a plurality of signal channels 90.sub.1 to 90.sub.n. A plurality of first connecting devices 50.sub.1 to 50.sub.n are preferably arranged in the vicinity of the left-hand edge of the carrier board 40. The first connecting devices 50.sub.1 to 50.sub.n are preferably arranged on an imaginary line that runs parallel to the y-axis of the coordinate system shown in FIG. 1 and thus perpendicular to the longitudinal axis of the carrier board 40. A field instrument can be connected to each first connecting device. Such a field instrument 30 is shown in FIG. 2 by way of example.

[0028] The signal channels 90.sub.1 to 90.sub.n preferably run parallel to one another, specifically on imaginary lines that run parallel to the x-axis of the coordinate system shown in FIG. 1 and thus parallel to the longitudinal axis of the carrier board 40. Since the signal channels in the present example are substantially identical to one another, their structure is only described in more detail in connection with the signal channel 91.sub.1 for the sake of simplicity. The explanation of the signal channel 90.sub.1 is from left to right with respect to the interface arrangement 10 shown in FIG. 1.

[0029] The signal channel 90.sub.1 has the first connecting device 50.sub.1 which is preferably connected to a first electrical connector 70.sub.1 via a first signal line portion 91.sub.1. The first connector 70.sub.1 can be designed as a socket or plug of a plug-in connection. An interface 100.sub.1 is mounted on the carrier board 40 between the first connecting device 50.sub.1 and the first connector 70.sub.1. The electrical interface 100.sub.1 is designed for releasable accommodation of a surge protection module. The surge protection module is preferably designed as a plug-in module, so that the interface has a corresponding mechanical configuration in order to be able to accommodate plug-in modules. The electrical interface 100.sub.1 contains at least two electrical contacts 101.sub.1 and 102.sub.1 which can be connected to corresponding contacts of the surge protection module.

[0030] An electrical resistor 130.sub.1 is connected to the first signal line portion 91.sub.1 or to the contacts 101.sub.1 and 102.sub.1 of the interface 100.sub.1 so that the interface arrangement 10 can also be operated correctly without surge protection modules being plugged in. The electrical resistor 130.sub.1 ensures that an increased current caused by surge voltages flows through the plugged-in surge module via the interface 100.sub.1. The respective surge module is designed in such a way that it has a low resistance at high voltages, so that the current no longer flows through the resistor 130.sub.1 or only to a harmless extent. A surge arrester 140 is provided having an electrical conductor 141 which is electrically connected to each interface 100.sub.1 to 100.sub.n or to the respective first signal line portions 91.sub.1 to 91.sub.n, so that the high currents that occur in the event of a surge voltage do not flow through the signal processing devices. The electrical conductor 141 is preferably connected to a ground connection 145 which is preferably arranged on the carrier board 40. As shown in FIG. 1, the ground connection 145 can be connected to ground or to a mounting rail (not shown) onto which the interface arrangement 10 can be latched.

[0031] As can also be seen in FIG. 1, the first signal line portion 91.sub.1 of the signal channel 90.sub.1 is connected to the connector 70.sub.1. In the example shown, the connector 70.sub.1 is connected indirectly to the second connecting device 60.sub.1 via a second signal line portion 92.sub.1, a manually operable safety device 120.sub.1 and a third signal line portion 93.sub.1.

[0032] The second connecting devices 60.sub.1 to 60.sub.n are preferably located in the vicinity of the right-hand edge of the carrier board 40 and are arranged on an imaginary line that runs parallel to the y-axis of the coordinate system shown in FIG. 1. It is also conceivable to connect the connector 70.sub.1 directly to the second connecting device 60.sub.1 via the second signal line portion 92.sub.1. One advantage of the manually operable safety device 120.sub.1 is that the respective signal channel, here the signal channel 90.sub.1, can be interrupted directly by an operator in an emergency.

[0033] As can be seen in FIG. 1, the interface arrangement 10 has, for example, n=16 signal channels 90.sub.1 to 90.sub.n, 16 first connecting devices 50.sub.1 to 50.sub.n, 16 interfaces 100.sub.1 to 100.sub.n, 16 connectors 70.sub.1 to 70.sub.n and, correspondingly, 16 second connecting devices 60.sub.1 to 60.sub.n, each of which is arranged on an imaginary line which runs parallel to the y-axis of the coordinate system shown in FIG. 1. All signal channels or second connecting devices 60.sub.1 to 60.sub.n are designed to be connected to a control device, for example the programmable logic controller 20 shown in FIG. 2.

[0034] FIG. 2 is a cross-sectional view through the interface arrangement 10 shown in FIG. 1 along the first signal channel 90.sub.1.

[0035] FIG. 2 shows a cross-section through the carrier board 40 and a field instrument 30 connected to the first connection 50.sub.1, which can be a sensor or an actuator. As shown by way of example in FIG. 2, the first signal line portion 91.sub.1 of the signal channel 90.sub.1 runs within the carrier board 40 up to the first electrical contact 101.sub.1 of the interface 100.sub.1, continuing via the electrical resistor 130.sub.1, the second electrical contact 102.sub.1 of the interface 100.sub.1 to a first contact point 71.sub.1 of the first connector 70.sub.1. It can also be seen in FIG. 2 that a surge protection module 110 is plugged into the interface 100.sub.1. As already mentioned, the surge protection module 100.sub.1 serves to conduct a high current via the surge protection module 110 in the resistor 130.sub.1 in the event of a surge voltage.

[0036] Furthermore, a signal processing device 80 can be seen in FIG. 2, which is electrically and mechanically connected to the first connector 70.sub.1. For this purpose, the signal processing device 80 has a connector 81 designed to be complementary to the first connector 70.sub.1.

[0037] The second signal line portion 92.sub.1 runs from a second contact point 72.sub.1 of the first connector 70.sub.1, for example partially in and on the carrier 40 up to the manually operable safety device 120.sub.1. As can be seen from FIG. 2, the two signal line portions 91.sub.1 and 92.sub.1 are electrically connected to one another only when the signal processing device 80 is connected to the first connector 70.sub.1. An electrical connection of the signal channel 90.sub.1 is thus only established when the signal processing device 80 is electrically connected to the first connector 70.sub.1. A field instrument 30 acting as a sensor can then be fed to the signal processing device 80 via the signal line portion 91.sub.1, the electrical resistor 130.sub.1, processed accordingly by said signal processing device and then fed to the PLC 20 for further processing via the second signal line portion 92.sub.1, the manually operable safety device 120.sub.1, via the third signal line portion 93.sub.1 and via the second connecting device 60.sub.1.

[0038] The interface arrangement 10 ensures that the field instruments connected to the first connecting devices 50.sub.1 to 50.sub.n can be assigned correctly to the corresponding inputs or outputs of the control device 20. Depending on the implementation, analog input signals of the sensor 30 can be fed to the signal processing device 80 via the signal channel 90.sub.1, converted there into digital signals and fed to a digital input of the control device 20 via the connecting device 60.sub.1. Similarly, depending on the implementation, analog output signals of the control device 20 can be fed to an actuator (not shown) having an analog input, for example via the signal channel 90.sub.n, via the second connecting device 60.sub.n, a signal processing device that is electrically connected to the connector 70.sub.n, and via the first connecting device 50.sub.n.

[0039] It should also be noted that the interfaces 100.sub.1 to 100.sub.n can each be in the form of electrical plug or socket connectors.

[0040] An alternative interface arrangement 11 is shown in FIGS. 3 and 4, which is designed for connecting a plurality of field instruments to at least one control device, with signals from and to the field instruments being sorted, processed and/or converted depending on the implementation.

[0041] One difference from the interface arrangement 10 is that the interface arrangement 11 has a plurality of carrier boards, which allow for a more flexible structure and thus easier adaptation to different areas of use and applications. For this purpose, interfaces 180.sub.1 to 180.sub.n for connecting surge protection modules to at least one first carrier board 150 and electrical connectors 290.sub.1 to 290.sub.n for connecting signal processing devices to a second carrier board 160 are arranged. FIG. 3 will be considered first.

[0042] FIG. 3 is a plan view of the alternative interface arrangement 11 without surge protection modules and without plugged-in signal processing devices, which are shown in FIG. 4.

[0043] The interface arrangement 11 has at least one first carrier board 150, which in turn has a plurality of first signal channels, for example eight signal channels 270.sub.1 to 270.sub.8. In the present example, the interface arrangement 11 has two first carrier boards, namely the carrier board 150 and a further carrier board 151, which in turn has a plurality of signal channels, for example also eight signal channels 270.sub.9 to 270.sub.n. The interface arrangement 11 thus has 16 signal channels.

[0044] Since the two carrier boards 150 and 151 can be of substantially the same design, only the structure of the carrier board 150 is explained in more detail below.

[0045] Each of the signal channels 270.sub.1 to 270.sub.8 preferably has a first connecting device in the vicinity of a first edge of the carrier board 150 and a second connecting device on the opposite edge of the carrier board 150. In other words, the signal channel 270.sub.1 has the first connecting device 190.sub.1 and the second connecting device 220.sub.1, while the eighth signal channel 270.sub.8 has a first connecting device 190.sub.8 and a second connecting device 220.sub.8. The first connecting devices 190.sub.1 to 190.sub.8 are designed for connection to a respective field instrument. The field instrument can be an actuator or a sensor with an analog or digital output. The second connecting devices 220.sub.1 to 220.sub.8 are designed in such a way that they can be electrically connected to third connecting devices 230.sub.1 to 230.sub.8 of the second carrier board 160. In the interface arrangement 11 shown by way of example in FIG. 3, the third connecting devices 230.sub.1 to 230.sub.n are covered by the two carrier boards 150 and 151; however, they can be seen in FIG. 4. It should already be noted at this point that the two first carrier boards 150 and 151 and the carrier board 160 can alternatively each be connected at their end faces, in which case the second connecting devices 220.sub.1 to 220.sub.n are then arranged, for example, at the outermost edge or at the end face of the carrier boards 150 and 151, while the third connecting devices 230.sub.1 to 230.sub.n can be arranged on the extreme left-hand side of the carrier board 150 or on the end face thereof.

[0046] Each of the signal channels 270.sub.1 to 270.sub.n has an electrical interface 180.sub.1 to 180.sub.n, each electrical interface being designed for releasable connection of a respective surge module. The interfaces 180.sub.1 to 180.sub.8 can in turn each be designed as a plug or socket connector.

[0047] The electrical interfaces 180.sub.1 to 180.sub.8 are arranged between the first connecting device and the second connecting device of the respective signal channel. For example, the electrical interface 180.sub.1 is arranged between the first connecting device 190.sub.1 and the second connecting device 220.sub.1. Each electrical interface is connected to an electrical resistor. Thus, the electrical interface 180.sub.1 is connected to an electrical resistor 210.sub.1 while the electrical interface 180.sub.8 is connected to an electrical resistor 110.sub.8. Furthermore, the first carrier board 150 has a surge arrester 200 which is arranged at least partially on and/or in the first carrier board 150 and is designed to arrest surge voltages and/or surge currents which may occur. In a similar manner, the further first carrier board 151 has a surge arrester 202 which is electrically connected to the interfaces 270.sub.9 to 270.sub.n.

[0048] In one embodiment, each first signal channel 270.sub.1 to 270.sub.8 of the carrier board 150 has at least one first signal line portion 271.sub.1 to 271.sub.8 which extends from the first connecting device of the respective first signal channel to the second connecting device. In other words, the signal line portion 271.sub.1 of the first signal channel 270.sub.1 extends from the first connecting device 190.sub.1 to the second connecting device 220.sub.1.

[0049] As can be seen in FIG. 3, the electrical resistors 210.sub.1 to 210.sub.8 are connected to the respective signal line portion 271.sub.1 or 271.sub.8 or to two electrical contacts 211.sub.1-211.sub.8 and 212.sub.1-212.sub.8 of the respective interface 180.sub.1-180.sub.8. Furthermore, FIG. 3 shows by way of example that the surge arrester 200 comprises an electrical conductor which runs at right angles to the first signal line portions 271.sub.1 to 271.sub.8. In other words, the electrical conductor of the surge arrester 200 is aligned on an imaginary line that is arranged parallel to the y-axis, while the signal line portions 271.sub.1 to 271.sub.8 run parallel to the x-axis of the coordinate system shown in FIG. 3. A ground connection 201, which is connected to the electrical conductor of the surge arrester 200, can be arranged on the first carrier board 150. Similarly, a further ground connection 203 can be arranged on the further first carrier board 151, which is electrically connected to the electrical conductor of a surge arrester 202.

[0050] The carrier board 151 has the remaining signal channels 270.sub.9 to 270.sub.n which, as mentioned above, can be constructed substantially identically to the signal channels 270.sub.1 to 270.sub.8 that have been described above. As FIG. 3 shows, the first connecting devices 190.sub.1 to 190.sub.n, the interfaces 180.sub.1 to 180.sub.n and the second connecting devices 220.sub.1 to 220.sub.n are each arranged on an imaginary line that runs parallel to the y-axis of the coordinate system shown in FIG. 3.

[0051] It should be noted at this point that the two first carrier boards 150 and 151 and the second carrier board 160 can be designed so as to be electrically and mechanically coupled to one another. For this purpose, the carrier boards can have corresponding latching elements which allow the carrier boards to be mechanically fixed and held together.

[0052] The second carrier board 160 has a plurality of second signal channels 280.sub.1 to 280.sub.n, which in turn each have one of the third connecting devices and each have a fourth connecting device and are arranged in alignment with the first signal channels 270.sub.1 to 270.sub.n in the coupled state. For example, the second signal channel 280.sub.1 has the third connecting device 230.sub.1 and the fourth connecting device 250.sub.1. As already mentioned, the third connecting devices 230.sub.1 to 230.sub.n are intended to be electrically connected to the second interfaces 220.sub.1 to 220.sub.n of the two first carrier boards 150 and 151. At least one control device can be connected to the carrier board 160 at the fourth connecting devices 250.sub.1 to 250.sub.n. It should also be noted that both the signal channels 270.sub.1 to 270.sub.n and the signal channels 280.sub.1 to 280.sub.n substantially run parallel to one another, i.e. parallel to the x-axis of the coordinate system shown in FIG. 3.

[0053] As FIG. 3 shows, when installed, the second connecting devices 220.sub.1 to 220.sub.8 of the first carrier board 150 are connected to the corresponding third connecting devices, of which only the connecting device 230.sub.1 is shown in FIG. 4, while the second connecting devices 220.sub.9 to 220.sub.n of the first carrier board 151 are electrically connected to the corresponding third connecting devices on the carrier board 160.

[0054] Furthermore, an electrical connector 290.sub.1 to 290.sub.n is arranged between the third and fourth connecting device of each second signal channel 280.sub.1 to 280.sub.n. For example, the connector 290.sub.1 is arranged between the third connecting device 230.sub.1 and the fourth connecting device 250.sub.1 of the signal channel 280.sub.1. The connectors 290.sub.1 to 290.sub.n can each be implemented as plugs or sockets and designed for electrical and mechanical connection to a second, complementary connector of a signal processing device. A corresponding complementary connector 241 is shown with regard to a signal processing device 240 in FIG. 4.

[0055] Each second signal channel 280.sub.1 to 280.sub.n can have a first signal line portion, which extends from the first connecting device of the respective signal channel to a first electrical contact of the respective connector, and at least one second signal line portion, which extends from a second electrical contact of the respective electrical connector either directly or indirectly via a safety device 260.sub.1-260.sub.n to the respective fourth connecting device. Referring to the second signal channel 280.sub.1, its first signal line portion 281.sub.1 extends from the third connecting device 230.sub.1 to the first electrical contact 291.sub.1 of the electrical connector 290.sub.1, while the second electrical contact 292.sub.1 of the electrical connector 290.sub.1 is connected to the fourth connecting device 250.sub.1 via a signal line portion 282.sub.2, the safety device 260.sub.1 and a further signal line portion 283.sub.1. As can be seen in FIG. 3, the further signal channels 280.sub.2 to 280.sub.n are of substantially identical design to the signal channel 280.sub.1. In other words, each electrical connector 290.sub.1-290.sub.n is preferably connected to the respective fourth connecting device 250.sub.1-250.sub.n via one of the manually operable safety devices 260.sub.1 to 260.sub.n.

[0056] FIG. 4 is a cross-sectional view of the interface arrangement 11 shown in FIG. 3 along the signal channels 270.sub.1 and 280.sub.1, with the first carrier board 150 and the second carrier board 160 being shown in the separated state.

[0057] FIG. 4 shows the carrier board 150 in cross-section with the first connecting device 190.sub.1, which is attached as a connecting contact on the upper side of the carrier board 150. Also shown is the second connecting device 271.sub.1, which is arranged, for example, on the underside of the carrier board 150. The connecting device 190.sub.1 is connected to the connecting device 220.sub.1 via the signal line portion 271.sub.1, the signal line portion 271.sub.1 preferably running in the carrier board 150. The electrical resistor 210.sub.1 is connected to the signal line portion 271.sub.1 via its connecting contacts 211.sub.1 and 212.sub.1, which in turn can be electrically connected to the contacts 181.sub.1 and 182.sub.1 of the interface 180.sub.1, which is arranged on the upper side of the carrier board 150.

[0058] As can be seen further in FIG. 4, the signal line portion 271.sub.1 is connected to the electrical conductor of the surge arrester 200 which in turn is connected to the ground connection 201. The ground connection 201 can, for example, be electrically connected to ground or a top hat rail in order to be able to divert surge currents caused by surge voltage.

[0059] FIG. 4 also shows a surge protection module 170, which can be designed in the form of a plug-in module. The interface 180.sub.1 is preferably designed to accommodate plug-in modules. Currents caused by surge voltages are substantially routed through the surge protection module 170, which is indicated by the dashed line in the surge protection module 170.

[0060] Furthermore, FIG. 4 shows a cross-section through the second carrier board 160, specifically along the signal channel 280.sub.1.

[0061] The third connecting device 230.sub.1 and the fourth connecting device 250.sub.1 are arranged on the upper side of the carrier board 160. The first signal line portion 281.sub.1 preferably runs within the carrier board 160 and connects the third connecting device 230.sub.1 to the contact 291.sub.1 of the electrical connector 290.sub.1. The second signal line portion 282.sub.1 preferably runs in segments within the carrier 160 and in segments on the carrier 160 and connects the contact 292.sub.1 of the electrical connector 290.sub.1 to a first contact of the manually operable safety device 260.sub.1. The third signal line section 283.sub.1 preferably runs in segments within the carrier 160 and in segments on the carrier 160 and connects a second contact of the manually operable safety device 260.sub.1 to the connecting device 250.sub.1.

[0062] Furthermore, FIG. 4 shows the signal processing device 240 which is electrically and mechanically connected to the connector 290.sub.1 and has an electrical connector 241 which is complementary to the connector 290.sub.1. According to an advantageous embodiment, the signal line portion 281.sub.1 is only electrically connected to the signal line portion 282.sub.1 when the signal processing device 240 is electrically connected to the connector 290.sub.1 mounted on the carrier board 160. This state is represented symbolically by the dashed line 242. In other words, only in the mounted state can field signals from a field instrument connected to the connecting device 190.sub.1 reach the fourth connecting device 250.sub.1, a predetermined signal processing and/or signal conversion being performed in the signal processing device 240.