WO2018184766A1

WO2018184766A1 - Power-over-ethernet-based field device used in automation technology

Info

Publication number: WO2018184766A1
Application number: PCT/EP2018/054928
Authority: WO
Inventors: Tobias Paul; Harald SCHÄUBLE
Original assignee: Endress+Hauser SE+Co. KG
Priority date: 2017-04-07
Filing date: 2018-02-28
Publication date: 2018-10-11
Also published as: DE102017107535A1

Abstract

Power-over-Ethernet-based field device used in automation technology, comprising: – a field device housing (61); – a sensor and/or actuator (62) for determining and/or setting a process variable; – an Ethernet port (63), arranged on the field device housing, for connecting the field device to an Ethernet-based network (70), so that the field device is suppliable with power via the Ethernet port and can interchange data with the network; – at least one further supplying field device port (64), arranged on the field device housing (61), for connecting at least one further field device (20, 30), – field device electronics (65) set up to supply the at least one further field device port (64) with power, so that a further field device (20, 30) connected to the further field device port (64) is suppliable with power and is further set up to interchange data with the further field device (20, 30), so that data are communicable between the Ethernet-based network and the further field device connected to the further field device port.

Description

Power over Ethernet-based field device of automation technology

The invention relates to a Power over Ethernet-based field device of

Automation technology as well as a system of automation technology.

In automation technology, in particular in process automation technology, field devices are often used which serve for the detection and / or influencing of process variables at a measuring point, in an automation system. For the detection of process variables are sensors, such as

Level gauges, flowmeters, pressure and temperature measuring devices, pH redox potential measuring devices, conductivity meters, etc., which record the corresponding process variables level, flow, pressure, temperature, pH or conductivity. To influence process variables, actuators, such as valves or pumps, are used to control the flow of a liquid in a single fluid

Pipe section or the level can be changed in a container. In principle, field devices are all devices that are used close to the process and that provide or process process-relevant information. In the context of the invention, field devices are therefore in particular also remote I / Os,

Radio adapter or generally understood devices that are arranged on the field level.

A variety of such field devices is manufactured and sold by the company Endress + Hauser.

Power over Ethernet (in the following also: PoE) designates a possibility with which networkable devices are also supplied with power via the Ethernet cable. For this purpose, the standard IEEE 802.3-2015 was published in February 2015, in which also the published in July 2003 standard IEEE 802.3af completely flowed.

Increasingly, Power over Ethernet is also used in the

Automation technology, especially in the field devices described above.

Nonetheless, these days there are a large number of existing ones

Automation systems still two- or four-wire field devices, which are connected via a two- or four-wire wiring with each other and at least one parent unit, for example. A control unit PLC, common. The two- or four-wire field devices known from the prior art are designed such that the measured value communicates in an analog manner via the two-wire wiring or the two-wire line, i. is transmitted. The transmission is usually based on the 4 to 20 mA standard. In addition, there is also a large number of bus-powered field devices in the existing automation systems, which have one in the

Automation technology common field bus with each other and at least one parent unit are connected. The bus-powered field devices known from the prior art are designed such that the measured value is communicated digitally via the fieldbus. Since usually the wiring of such an automation system, especially in the case that is to be switched from two- or four-wire field devices or bus-powered field devices on Power over Ethernet based field devices, a significant cost, it is desirable that a high cabling effort is avoided.

It is therefore an object of the invention to provide a way by means of which existing automation systems with the lowest possible

Cabling overhead can be converted to Pover over Ethernet-based field devices.

The object is achieved by a power over Ethernet-based field device of automation technology, comprising:

a field device housing;

a sensor and / or actuator for determining and / or setting a process variable; an Ethernet connection arranged on the field device housing for connecting the field device to an Ethernet-based network, so that the field device can be supplied with energy via the Ethernet connection and can exchange data with the network;

at least one arranged on the field device housing further feeding field device connection for connecting at least one further field device, a field device electronics is adapted to provide the at least one further field device connection with energy, so that a connected to the other field device connection further field device can be supplied with energy and further set up is, data with the other field device

so that data can be communicated between the Ethernet-based network and the other field device connected to the further field device connection.

According to the invention, use is made of the fact that when powering a field device at a measuring point by means of Power-Over-Ethernet, a power of 3.84 W is already available in the smallest class at the terminal, ie the field device. This power is not completely required by the field device of the measuring point itself, so that it is possible according to the invention to supply at least one further field device, which is correspondingly connected to the field device fed by means of Power Over Ethernet, with energy. The Power Over Ethernet based field device is included according to the invention arranged such that it communicates data, in particular measured values, with the connected field device, process them and can pass on accordingly. In this way, a step-by-step conversion of the existing automation systems to Power over Ethernet can take place without great initial costs and with minimal wiring effort.

An advantageous development of the invention provides that the at least one further field device connection is set up so that at least one field device, which is configured to transmit at least one measured value digitally, can be connected as a further field device and the field device electronics are furthermore configured such that the at least one connected to the further field device terminal field device, which is adapted to transmit at least one measured value digitally, is supplied with energy and that data between the Ethernet-based network and the at least one field device can be communicated. In particular, the

Further, provision is made for the field device electronics to be set up such that the at least one field device, which is set up to transmit at least one measured value digitally, can transmit the at least one measured value according to one of the following protocols:

a HART protocol, which preferably provides a multidrop mode, a Profibus PA protocol, or

a Foundation Fieldbus (FF) protocol.

An alternative development of the invention provides that the at least one further field device connection is set up as a further field device, a field device, which is adapted to transmit at least one measured value analog, connectable and the field device electronics is further adapted to that on field device connectable to the field device field device, which is adapted to transmit at least one measured value analog, according to an analog 4 to 20-mA standard can be supplied with energy and that data with the at the other

Field device connection connectable field device according to the 4 to 20 mA standards are communicable.

The object is also according to the invention by a system of

Automation technology solved, comprising an automation system with at least: an Ethernet-based network;

a Power over Ethernet-based field device according to a previously

described embodiment;

a Power over Ethernet cable that connects the Ethernet-based network to the Power over Ethernet-based field device via the Ethernet port; and at least one further non-Power over Ethernet-based field device, wherein the further field device is connected to the further supplying field device connection of the Power over Ethernet-based field device, so that the further supplying field device connection supplies the further field device with energy and further serves that the further Power over Ethernet-based field device data can not communicate with the Ethernet-based network through the Power over Ethernet-based field device.

An advantageous development of the system provides that the at least one further field device is designed as a field device, which is set up to transmit at least one measured value digitally, and the system further comprises a field bus, which is at least the field device which is set up. to transmit at least one measured value digitally connected to the further supplying field device connection of the Power over Ethernet-based field device, wherein the field device electronics is further configured to supply the field device connected to the field device connection with energy and data connected to the field device connected to the field device to communicate over the fieldbus according to a bus protocol. Preferably, the development may further comprise a plurality of field devices, which are each configured to transmit at least one measured value, which are connected via the fieldbus to the Power over Ethernet-based field device, wherein the field device electronics is further adapted to the multiple field devices with energy to supply and communicate data with the several other field devices according to the bus protocol. The development can very particularly preferably provide that the fieldbus is designed as a HART fieldbus, a Profibus PA or an FF and the further field device or the further field devices is or are configured to have the at least one measured value corresponding to the

to transmit the trained fieldbus.

An alternative development for this purpose can provide that the further field device is designed as a field device which is set up to transmit at least one measured value analogously and the system further comprises a two-wire connection, which includes the further field device with the further supplying field device connection of the Power over Ethernet -based field device connects, wherein the field device electronics is further configured to provide the field device connected to the field device via the two-wire connection according to a 4 to 20-mA standard with power and data to the other field device according to the 4 to 20-mA standard communicate.

A further advantageous development can provide that the automation system a hazardous area and a non-hazardous area which does not have the Power over Ethernet based field device

potentially explosive area and the at least one further non-Power over Ethernet-based field device, which is fed via the field device connection of the Power over Ethernet-based field device, is arranged in the potentially explosive area.

The invention will be explained in more detail with reference to the following drawings. It shows:

Fig. 1 a: an example of a known from the prior art

Automation system in which the field devices of the individual measuring points are each connected via a two-wire line to a higher-level unit,

Fig. 1 b: an example of a known from the prior art

Automation system in which the field devices of the individual measuring points are connected to a higher-level unit via a fieldbus,

2 a shows an example of a design of an automation system with Power-over-Ethernet-based field devices, FIG. 2 b shows an example of a configuration of an automation system with Ethernet-based field devices, which are supplied with energy via their own energy supply unit, FIG.

3 is a schematic representation of a first embodiment of a power over Ethernet-based field device according to the invention, and

Fig. 4: an automation system with a hazardous area and a non-hazardous area in which the power over Ethernet-based field device according to the invention is preferably used.

Figure 1 a shows an example of a known from the prior art

Automation system in which the field devices 20 and 30 of the individual measuring points via a two-wire line 21 to a parent unit 10, for example. A programmable logic controller (short: PLC) are connected. For example, the automation system shown may refer to measuring or monitoring a level of a tank and includes two two-wire field devices 20, the first two-wire field device 20, the level by radar and the second field device 20, the temperature of the medium to calculate a normal volume measures , According to the systems known from the prior art, the two two-wire field devices 20 are connected to the PLC 10 via a two-wire line 21 for this purpose, both to transmit data, in particular the measured value, as well as to be supplied with energy. The two-wire field devices 20 are designed to communicate the data in such a way that they convert the data into an analog current signal, for example the analogue 4 ... 20 mA current signal common in automation technology, and vice versa. The communication between the two-wire field devices 20 and the PLC 10 is then via the analog 4 ... 20 mA current signal.

In the HART specification (Abbreviation for "Highway Addressable Remote Transducer"), which is also known in the art and which on the previously

Based on the described technology, the data is transmitted by Frequency Shift Keying (FSK) by superimposing a high-frequency oscillation on the low-frequency analog current signal. Here, a digital "1" with a specific frequency of 1, 2 kHz and a digital "0" with a specific frequency of 2.2 kHz is shown. HART thus leaves a digital one

Communication over the two-wire connection, each field device 30 is connected via a two-wire connection 21 to the parent unit 10. In addition, HART also allows a digital communication to multiple field devices 30 via a common data bus or field bus 31. 1 b shows an example of such a structure of an automation system, in which the field devices 30 of the individual

Measuring points are connected via a common fieldbus 31 to the parent unit 10. Here, the HART specification provides a so-called multidrop operation. In multidrop operation, the superordinated unit 10, for example the

Control unit, the current for operating the fieldbus 31 connected to the field devices 30 available by impressing a current of 4 mA on the field bus 31 for feeding and each parallel to the fieldbus connected field device 30 is set up such that it data with about +/- 0.5 mA modulated onto the impressed current for HART communication.

In addition to the HART specification, there are also other known in the art fieldbus specifications, according to which a communication of the field devices in an automation system can be realized via a single fieldbus 31. For example, the field devices can also communicate according to the Profibus standard, in particular Profibus PA / FF. The basic structure of a corresponding

Automation system substantially corresponds to the structure shown in Fig. 1 b.

FIG. 2 a shows by way of example a basic structure of an automation system with Power-over-Ethernet-based field devices. In this case, all field devices 40 used with the higher-level unit 10, for example, a PoE switch, respectively via a

corresponding PoE cable 41 connected because Power over Ethernet no

Cascading allows. Any connected PoE-based will be via the PoE cable Field device 40 is powered and can communicate its data in accordance with the Ethernet standard.

As already described above, this leads to the conversion of existing automation systems with two-wire field devices that transmit their data analog, or with bus-powered field devices that transmit their data digitally, eg. HART, HART multidrop or Profibus PA / FF, at a considerable extra expense in terms of cabling and / or costs. So have in the conversion of

Automation systems with field devices that transmit data digitally over a fieldbus, as shown by way of example in Fig. 1 b, Ethernet-based field devices 50 are used with switching functionality without Power over Ethernet, each having its own power supply 52, eg. A power supply , (Fig. 2b). In this case, a high additional effort would be necessary when changing to Power over Ethernet, because a new wiring for powering the field devices would have to be installed.

3 shows a schematic representation of a first exemplary embodiment of a Power over Ethernet-based field device 60 according to the invention. The field device 60 has a field device housing 61, depending on the configuration, a sensor and / or an actuator 62, an Ethernet connection 63, which is arranged on the field device housing 61 is and a field device electronics 65, which controls the sensor and / or actuator 62 and controls the provided by the field device 60 provided functionality on. Furthermore, according to the invention, the field device 60 has at least one further field device connection 64, which is likewise arranged on the field device housing 61. The at least one further field device connection is designed in such a way and connected to the field device electronics, that a further field device 20 or 30 connected to the further field device connection can be supplied with energy.

The field device electronics 65 of the field device according to the invention is designed for this purpose such that the energy in the PoE-based field device 60 via the

Ethernet port 63 is provided, in part, the at least one other

Field device 20 or 30 is available when it is connected to the other field device port 64. Furthermore, the field device electronics 65 are set up so that data can be communicated between the Ethernet connection 63 of the PoE-based field device 60 and the at least one field device 20 or 30 connected to the further field device connection 64, so that the PoE-based field device as it were

Switching station acts.

By means of the at least one further field device connection 64, either an ordinary two-wire field device 20, as shown in FIG. 1a and described accordingly, or a bus-fed field device 30, as shown in FIG is described accordingly connected. Furthermore, a number of bus-fed field devices 30 can also be connected to the further field device connection 64

be connected so that, depending on how much energy is finally available in the PoE-based field device 60, an entire

Field device branch of an existing automation system can be connected. In this case, the field device electronics 65 are configured so that the bus-powered field devices 30 connected in series can communicate their respective data with the PoE-based field device 60 via a corresponding Ethernet tunnel. In this way, the implementation effort at the system level or

Field device level minimum and the gradual conversion of an existing

Automation system with bus-powered field devices can be additionally facilitated.

In addition, however, it can also be provided that the PoE-based field device 60 has a plurality of further field device connections 64 which are arranged on the field device housing 61, so that a plurality of further field devices 20 and 30 can be connected. In this case, the PoE-based field device 60 may be designed such that both a plurality of further bus-fed field devices 30 can be connected to the several other field device connections 64 or that a further two-wire field device 20 can be connected to each further field device connection 64.

Of course, the PoE-based field device 60 may also be designed in such a way that both bus-fed field devices 30 and two-wire field devices 20 can be connected via respectively different further field device connections 64. With regard to the bus-fed field devices 30, in particular such field devices come into consideration, which transmit their data according to the HART protocol, the Profibus PA or FF protocol.

As shown by way of example in FIG. 4, the PoE-based field device according to the invention can be used in particular in automation systems with explosion-endangered 80 and non-hazardous areas 90. Thus, the PoE-based field device 60 can be arranged, for example, in the non-hazardous area 90 and at least one further field device in the form of a two-wire field device 20 or a bus-powered field device 30, which is arranged in the explosion-hazard region 80 via the at least one further field device connection 64 be connected. List of Reference Signs Control room or PLC

Field device which is set up to transmit a measured value analogously

Two-wire connection

Field device which is set up to digitally transmit a measured value

Fieldbus, especially HART Multidrop, Profibus PA / FF

PoE field device according to the prior art

PoE cable

Ethernet field device according to the prior art

Ethernet cable

power adapter

PoE field device according to the invention

Field device housing

Sensor and / or actuator

Ethernet connection

further feeding field device connection

Field device electronics

Ethernet-based network

Hazardous area

Non-hazardous area

Claims

claims

A power over Ethernet-based field device of automation technology comprising: a field device housing (61);

a sensor and / or actuator (62) for determining and / or setting a

Process variable;

an Ethernet connection (63) arranged on the field device housing for

Connecting the field device to an Ethernet-based network (70) so that the field device can be powered via the Ethernet port and exchange data with the network;

at least one further feeding field device connection (64) arranged on the field device housing (61) for connecting at least one further field device (20, 30),

a field device electronics (65) which is set up to provide the at least one further field device connection (64) with energy, so that a further field device (20, 30) connected to the further field device connection (64) can be supplied with energy and is furthermore set up for this purpose To exchange data with the further field device (20, 30) so that data can be communicated between the Ethernet-based network and the further field device connected to the further field device connection.

2. Field device according to claim 1, wherein the at least one further field device connection (64) is configured such that at least one field device (30), which is configured to transmit at least one measured value digitally, can be connected as a further field device and the field device electronics (65 ) is further configured to provide energy to the at least one field device (30) connected to the further field device connection (64) and configured to transmit at least one measured value, and that data is transferred between the Ethernet-based network (70 ) and the at least one field device (30) are communicable.

3. Field device according to the preceding claim, wherein the field device electronics (65) is further adapted to the at least one field device (30), which is adapted to transmit at least one measured value digitally transmit the at least one measured values according to one of the following protocols can:

an FF protocol.

4. Field device according to claim 1, wherein the at least one further field device connection (64) is adapted to that as a further field device, a field device (20), which is arranged to transmit at least one measured value analogously, can be connected and the field device electronics (65) is further adapted to that at the other

Field device connection (64) connectable field device (20), which is adapted to transmit at least one measured value analog, according to an analog 4 to 20-mA standard with energy can be supplied and that data with the at the other

Field device connection (64) connectable field device (20) according to the 4 to 20 mA

Standards are communicable.

5. System of automation technology, comprising an automation system with at least:

an Ethernet based network (70);

a Power over Ethernet-based field device according to claim 1;

a Power over Ethernet cable (41) connecting the Ethernet based network (70) to the Power over Ethernet based field device (60) via the

Ethernet port (63) connects; and

at least one further non-Power over Ethernet-based field device (20, 30), wherein the further field device (20, 30) feeds at the further

Field device connection (64) of the Power over Ethernet-based field device (60) is connected, so that the further supplying field device connection (64) the further field device (20; 30) with energy and also serves that the other not Power over Ethernet based field device (20; 30) data with the Ethernet-based network (70) over the Power over Ethernet-based

Field device (60) can communicate.

6. System according to the preceding claim, wherein the at least one further field device (20; 30) as a field device (30) which is adapted to transmit at least one measured value digitally, and the system further comprises a field bus (31) at least the field device (30), which is adapted to transmit at least one measured value digitally, to the further feeding field device connection (64) of the Power over Ethernet-based field device (60), wherein the

Field device electronics (65) is further adapted to that at the other

Field device connection (64) connected field device (30) to provide energy and data to communicate with the field device connected to the field device (30) via the fieldbus (31) according to a bus protocol.

7. System according to the preceding claim, further comprising a plurality of field devices (30), which are each configured to transmit at least one measured value, which are connected via the fieldbus (31) to the Power over Ethernet-based field device (60), wherein the field device electronics (65) is further adapted to the to power several field devices (30) and to communicate data with the several other field devices (30) according to the bus protocol.

8. System according to claim 6 and / or 7, wherein the field bus is designed as a HART fieldbus, a Profibus PA or an FF and the further field device (30) or the further field devices (30) is / are set up, to transmit the at least one measured value corresponding to the trained fieldbus.

9. System according to claim 5, wherein the further field device (20; 30) is designed as a field device (20) which is set up to transmit at least one measured value analogously, and the system further comprises a two-wire connection (21) which comprises the further field device (20) connects to the further supplying field device connection (64) of the Power over Ethernet-based field device (60), the field device electronics (65) being further arranged to be connected to the further field device connection (64).

Connected field device (20) via the two-wire connection (41) according to a 4 to 20-mA standard to power and communicate data with the other field device according to the 4 to 20-mA standard.

10. System according to at least one of claims 5 to 9, wherein the

Automation system has a hazardous area (80) and a non-hazardous area (90), wherein the Power over Ethernet-based field device (60) in the non-hazardous area (90) and the at least one other non Power over Ethernet-based field device (20 30), which over the

Field device connection (64) of the Power over Ethernet-based field device is fed in the hazardous area (80) is arranged.