INTRINSICALLY SAFE ENERGY AND DATA TRANSMISSION IN AN ETHERNET NETWORK

Abstract

A transmission device for the intrinsically safe transmission of data in an Ethernet network via a core pair of an Ethernet cable is disclosed. The transmission device includes a first sub-path connected to a first wire of the core pair of an Ethernet signal pair and a second sub-path connected to a second wire of the core pair of the Ethernet signal pair. Each sub-path comprises at least one current-limiting resistor and a common-mode rejection unit connected in series to the current-limiting resistor.

Claims

1.-13. (canceled)

14. A transmission device for intrinsically safe data transmission in an Ethernet network using a core pair of an Ethernet cable, said transmission device comprising a first sub-path of an Ethernet signal pair connected to a first core of the core pair; and a second sub-path of an Ethernet signal pair connected to a second core of the core pair, each sub-path having at least one current-limiting resistor and a common-mode rejection unit that is connected in series with the current limiting resistor.

15. The transmission device of claim 14, wherein each sub-path has at least one isolating capacitor, which is connected in series with the common mode rejection unit and the at least one current limiting resistor.

16. The transmission device of claim 15, wherein each isolating capacitor has a capacitance such that data transmission is intrinsically safe and the signal flow that transmits the data is not obstructed by the impedance of the isolating capacitor.

17. The transmission device of claim 14, wherein each common-mode rejection unit is designed as a winding assembly that has one of two choke windings of a current-compensated choke and two diode current branches connected in parallel with the choke winding, wherein the two diode current branches of each winding assembly each have at least one diode, so that the two diode current branches have different blocking directions for electric current.

18. The transmission device of claim 14, wherein each sub-path is connected to a coupling coil by which electrical energy can be coupled into the core connected to the sub-path or can be coupled out from the core connected to said sub-path.

19. The transmission device of claim 18, wherein each coupling coil has an inductance which has at least a minimum inductance so that the coupling coil does not load data signals that are transmitted, and does not exceed a maximum inductance so that the data transmission is intrinsically safe.

20. An Ethernet network, comprising: a network device; an Ethernet cable having a core pair; and a transmission device configured to electrically connect the network device to the core pair of the Ethernet cable in an explosion-hazardous environment, said transmission device including a first sub-path of an Ethernet signal pair connected to a first core of the core pair, and a second sub-path of an Ethernet signal pair connected to a second core of the core pair, each sub-path having at feast one current-limiting resistor and a common-mode rejection unit that is connected in series with the current limiting resistor.

21. The Ethernet network of claim 20, wherein only data is transmitted over the Ethernet cable between said network device and another network device, and each core of the Ethernet core pair is connected to a respective one of said network devices by a respective transmission device.

22. The Ethernet network of claim 20, wherein both data and electrical energy are transmitted over the Ethernet cable between said network devices and each end of each core of said core pair is connected to said network devices by respective transmission devices.

23. The Ethernet network of claim 20, wherein each sub-path is connected to a coupling coil configured to couple electrical energy into or out from the core connected to said sub-path, wherein the inductance of each coupling coil of the transmission device depends on a data rate at which the transmission device transmits data.

24. The Ethernet network of claim 20, further comprising at least one of BroadR-Reach functionality or Long-Distance Ethernet functionality or 2-wire Ethernet functionality.

25. An intrinsically safe method of transmitting data from a first network device to a second network device in an Ethernet network having an Ethernet core pair, the first network device being connected to a first sub-path of an Ethernet signal pair that is connected to a first core of the Ethernet core pair and to a second sub-path of the Ethernet signal pair that is connected to a second core of the Ethernet core pair, wherein each sub-path has at least one current-limiting resistor and a common-mode rejection unit that is connected in series with the current limiting resistor, comprising: connecting the first network device to the second network device in an Ethernet network over an Ethernet core pair having a respective first and second sub-path, each sub-path having at least one current-limiting resistor and a common-mode rejection unit that is connected in series with the current limiting resistor; and transmitting data between the first network device and the second network device over said Ethernet core pair that is connected by the sub-paths to the network devices without transmitting data for a preliminary auto-negotiation step over said Ethernet core pair.

26. The method of claim 25 wherein the first and second network devices are each connected to the Ethernet core pair using a respective first and second sub-path that each have a coupling coil connected thereto, further comprising the step of coupling electrical energy through the respective core connected to each sub-path using a respective coupling coil.

27. The method of claim 26 wherein the first and second network devices are each connected to the Ethernet core pair using a respective first and second sub-path that each have a coupling coil, further comprising the step of selecting a coupling coil that has an inductance that is not less than a minimum inductance, such that the coupling coil does not load data signals, and that does not exceed a maximum inductance, such that the data transmission is intrinsically safe.

28. The method of claim 25, wherein all data is transmitted between the first network device and the second network device over said Ethernet core pair connected to the respective network devices by respective transmission devices at a data rate that is less than a specified minimum data rate.

Description

[0029] The properties, features and, advantages of the present invention described above and the manner in which these are achieved will become clearer and more comprehensible in conjunction with the following description of exemplary embodiments, which are explained in more detail in connection with the drawings. These show:

[0030] FIG. 1 a block diagram of a first exemplary embodiment of a transmission device for intrinsically safe data transmission in an Ethernet network,

[0031] FIG. 2 a block diagram of a second exemplary embodiment of a transmission device for intrinsically safe data transmission in an Ethernet network, and

[0032] FIG. 3 a block diagram of an Ethernet network.

[0033] Equivalent parts are provided with the same reference labels in all figures.

[0034] FIG. 1 shows a block diagram of a first exemplary embodiment of a transmission device 1 for intrinsically safe data transmission in an Ethernet network 100 (see FIG. 3) over a core pair (not shown) of an Ethernet cable 120 (see FIG. 3).

[0035] The transmission device 1 has two sub-paths 3, 5 of a conductor pair. A first sub-path 3 is connected to a first core of the core pair, which is connected to the end of the first sub-path 3, shown on the right in FIG. 1. The second sub-path 5 is connected to the second core of the core pair, which is connected to the end of the second sub-path 5, shown on the right in FIG. 1.

[0036] Each sub-path part 3, 5, has a current-limiting resistor 7, an isolating capacitor 9 connected in series with the current-limiting resistor 7, a common-mode rejection unit 11 which is connected in series with the current-limiting resistor 7 and the isolating capacitor 9 and is designed as a winding assembly, and a transceiver connection 13, via which the sub-path 3, 5 can be connected to a transceiver (not shown).

[0037] Each winding module has one of two choke windings 15 of a current-compensated choke 17, and two diode current branches 19, 21 connected in parallel with the choke winding 15. The two diode current branches 19, 21 of each winding assembly each have at least one diode 23, so that the two diode current branches 19, 21 have different blocking directions for electric current.

[0038] The choke windings 15 each have, for example, an inductance of 470 H. The isolating capacitors 9 each have, for example, a capacitance of 1.1 F.

[0039] FIG. 2 shows a block diagram of a second exemplary embodiment of a transmission device 1 for intrinsically safe data transmission in an Ethernet network 100 (see FIG. 3) over a core pair (not shown) of an Ethernet cable 120 (see FIG. 3). This exemplary embodiment differs from the exemplary embodiment shown in FIG. 1 essentially in the fact that each sub-path 3, 5 is connected to a coupling coil 25 and a coupling connection 27, via which electrical energy, which is transmitted over the core of the core pair in addition to data signals, can be coupled in or out. If electrical energy is decoupled via the coupling coils 25 and coupling connections 27, a decoupling diode is also connected between each coupling coil 25 and the coupling connection 27.

[0040] The choke windings 15 each have, for example, an inductance of 470 H. The isolating capacitors 9 each have, for example, a capacitance of 11 nF, The coupling coils 25 each have, for example, an inductance of 10 H.

[0041] Other exemplary embodiments of transmission devices 1, in contrast to the transmission devices 1 shown in FIGS. 1 and 2, have instead of one diode 23 in each diode current branch 19, 21 at least two parallel-connected diodes 23, and/or instead of one isolating capacitor 9 in each sub-path 3, 5 at least two isolating capacitors connected in series 9. In this case, the diodes 23 of a diode current branch 19, 21 and the isolating capacitors 9 of a sub-path 3, 5 are each designed to be identical (redundant). Such transmission devices 1 are preferably used in explosion-hazardous environments where an appropriate redundancy of diodes 23 and/or isolating capacitors 9 is required, for example due to regulations for the devices used in these explosion-hazardous environments.

[0042] FIG. 3 shows a block diagram of an Ethernet network 100 having a plurality of network devices 101 to 108, which belong to an automation system, for example. Six network devices 101 to 106, which can be arranged in an explosion-hazardous environment, are connected to one another via Ethernet cables 120 over which data are transferred, and form an intrinsically safe sub-network 200.

[0043] A first network device 101 of the sub-network 200 is connected via an Ethernet cable 120 to the sixth network device 106 of the sub-network 200 and is supplied with electrical power via this Ethernet cable 120.

[0044] A second network device 102 of the sub-network 200 is connected via an Ethernet cable 120 to a third network device 103 of the sub-network 200 and is supplied with electrical power via this Ethernet cable 120.

[0045] The other network devices 103 to 106 of the sub-network 200 are each supplied with electrical power by an electrical energy source 130. In this arrangement an Ethernet cable 120, over which only data (but no electrical energy) are transmitted, connects the third network device 103 to a fourth network device 104, the fourth network device 104 to a fifth network device 105 and the fifth network device 105 to the sixth network device 106.

[0046] To implement the intrinsic safety of the sub-network 200, two network devices 101 to 106 of the sub-network 200 connected via an Ethernet cable 120 are connected to the Ethernet cable 120 in each case via special interfaces 141, 142, which have transmission devices 1 shown in FIG. 1 or 2. Also, first interfaces 141 for Ethernet connections over which only data (but no electrical power) are transmitted, have a transmission device 1 shown in FIG. 1 for each core pair of an Ethernet cable 120 connected thereto, wherein if required, the diodes 23 and/or isolating capacitors 9 are implemented redundantly, as described above. By contrast, second interfaces 142 for Ethernet connections over which both data and electrical power are transmitted have a transmission device 1 shown in FIG. 2 for each core pair of an Ethernet cable 120 connected thereto, wherein the diodes 23 and/or isolating capacitors 9 are again implemented redundantly if required, as described above.

[0047] The interfaces 141, 142 also each have a transceiver, which is connected via transceiver connections 13 to each transmission device 1 of the respective interface 141, 142. Each transmission device 1 then forms an output of an interface 141, 142 to an Ethernet cable 120.

[0048] The Ethernet network 100 is designed in such a way that over cores of Ethernet cables 120 which are connected to a transmission device 1 of the type shown in FIG. 2 (with, if necessary, redundant diodes 23 and/or isolating capacitors 9, see above), only data with data rates that are not less than a minimum data rate, for example 100 Mbit/s, are transmitted. In this case, the minimum data rate is specified in such a way as to correspond to intrinsically safe inductances of the coupling coils 25 and capacitances of the isolating capacitors 9 of a transmission device 1 of the type shown in FIG. 2. The coupling coils 25 and capacitances of the isolating capacitors 9 of the transmission devices 1 of the type shown in FIG. 2 are also designed intrinsically safe.

[0049] Network devices 107, 108 arranged outside of the intrinsically safe sub-network 200 are connected as far as possible via optical connections 150, which extend between optical interfaces 160, to network devices 101 to 106 of the intrinsically safe sub-network 200. In the Ethernet network 100 shown in FIG. 3, a seventh network device 107 is connected to the third network device 103 in this way and an eighth network device 108 is connected to the sixth network device 106 in this way. The seventh network device 107 and the eighth network device 108 are additionally connected via conventional Ethernet interfaces 170 and Ethernet cables 120 to a residual network 110, not shown in detail here, the components of which have no direct connection to network devices 101 to 106 of the sub-network 200.

[0050] The third network device 103, the sixth network device 106, the seventh network device 107 and the eighth network device 108 are each designed, for example, as a switch of the Ethernet network 100. The remaining network devices 101, 102, 104, 105 shown are each designed, for example, as a terminal of the Ethernet network 100.

[0051] It is essential to the implementation of the intrinsic safety of the Ethernet network 100 that the sub-network 200 contains no conventional Ethernet interfaces 170, but only interfaces 141, 142 with outputs implemented by transmission devices 1 and optical interfaces 160 may be used for Ethernet connections. It is also essential that all transmission devices 1 of the type shown in FIG. 2 (with, if necessary, redundant diodes 23 and/or isolating capacitors 9, see above) are designed intrinsically safe, which is facilitated by the fact that they are only used for cores over which data are transmitted at data rates not less than the minimum data rate and, in particular, no auto-negotiation is performed.

[0052] Transmission devices 1 of the type shown in FIG. 1 (with, if necessary, redundant diodes 23 and/or isolating capacitors 9, see above) by contrast, can also be used for cores over which data are transmitted at data rates that are below the minimum data rate and in particular, auto-negotiation is routed, since these transmission devices 1 have no coupling coils 25 for coupling in electrical energy.

[0053] The intrinsic safety of the Ethernet network 100 is achieved by the fact that for Ethernet connections to be designed intrinsically safe, two different types of transmission devices 1 are used, namely a transmission device 1 of the type shown in FIG. 1 for Ethernet connections over which only data are transferred, and a transmission device 1 of the type shown in FIG. 2 for Ethernet connections over which energy is additionally transferred, wherein a minimum data rate for data transmissions is provided for these Ethernet connections to which the transmission device 1 of the type shown in FIG. 2 is matched.

[0054] Although the invention has been illustrated and described in greater detail by means of preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

LIST OF REFERENCE NUMERALS

[0055] 1 transmission device [0056] 3, 5 sub-path [0057] 7 current limiting resistor [0058] 9 isolating capacitor [0059] 11 common-mode rejection unit [0060] 13 transceiver connection [0061] 15 choke coil [0062] 17 current-compensated choke [0063] 19, 21 diode current branch [0064] 23 diode [0065] 25 coupling coil [0066] 27 coupling connection [0067] 100 Ethernet network [0068] 101 to 108, network device [0069] 110 residual network [0070] 120 Ethernet cable [0071] 130 electrical energy source [0072] 141, 142 interface [0073] 150 optical connection [0074] 160 optical interface [0075] 170 conventional Ethernet interface [0076] 200 sub-network