DE102015114442A1 - Method for activating an inactive interface on a field device of process automation - Google Patents

Abstract

The invention relates to a method for activating an inactive interface (3) on a field device (1) of process automation by means of an activation signal (Sa) and a field device (1) suitable for carrying out this method. For this purpose, according to the invention, an input signal is received at an active interface (2) and sent to an intelligent unit (5). The intelligent unit (5) checks whether the input signal is the activation signal (Sa). In the event that the input signal is the activation signal (Sa), the inactive interface (3) is activated. By the method it is possible to activate the inactive interface and thus via the interface (3) if necessary subsequently enter parameterization or calibration data, for example when the device is subjected to a revision or when the conditions of use of the field device (1 ) to change. At the same time, it can be ensured by the method that the interface (3) is inactive during regular operation and thus no unwanted data exchange can take place.

Description

The invention relates to a method for activating an inactive interface on a field device of process automation as well as a field device suitable for this purpose.

In automation technology, in particular in process automation technology, field devices are often used which serve to detect and / or influence process variables. Sensors that are used, for example, in level gauges, flowmeters, pressure and temperature measuring devices, pH redox potential measuring devices, conductivity meters, etc., which contain the corresponding process variables level, flow, pressure, temperature, pH value, redox potential, and so on, are used to record process variables Detect conductivity. To influence process variables are actuators, such as valves or pumps, via which the flow of a liquid in a pipe section or the level in a container can be changed. 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 thus also understood as remote I / Os, radio adapters or generally electronic components which are arranged on the field level. A variety of such field devices is manufactured and sold by the company Endress + Hauser.

Field devices usually have one or more interfaces for communicating with higher-level units, such as process control stations or operating and service personnel, but also for communication with one another. Due to the high degree of robustness, standard signals such as 4-20 mA or 0-10 V are usually used for measured value transmission as transmission standards. This makes it possible to realize the energy supply, the transmission of measured values and additional data transmission over a single two-wire line, if suitable transmission protocols such as "HART" or "Profibus" are used for this purpose. As a result, it is not necessary for many applications and fields of application that the field device has more than one interface.

However, to make parameterizations or calibrations, it may be very useful if the field device has one or more additional interfaces especially for these purposes. These additional interfaces can also be wired. However, it is reasonable to assume that these are wireless interfaces. This makes it possible to carry out parameter settings on the finished device without having to reopen the housing for calibration. As a wireless transmission standard, for example, wireless HART or Bluetooth can be used, with Bluetooth installed in almost all today's mobile devices. As a result, the field device is also via mobile devices, such as mobile phones or tablet PCs, configurable.

In particular, in wireless interfaces that are needed only during commissioning or manufacturing, it is expedient to disable them later, so that they are not accessible to unauthorized third parties later use. It also avoids having to obtain national radio licenses in the case of radio interfaces.

However, the deactivation of such interfaces is irreversible insofar as no data traffic can take place via this interface after deactivation. Accordingly, in contrast to deactivation via this interface, no signals for reactivation can be sent.

Thus, it is not possible via this interface, if necessary, subsequently enter parameterization or calibration data, for example, if the device is subjected to a revision or if the operating conditions of the field device change. This is particularly restrictive if no further operating interface (HMI, human-machine interface), such as a display / key unit, is present on the field device.

The invention is therefore based on the object to propose a method and a field device suitable for this, which enables activation of an inactive interface.

• – An einer aktiven Schnittstelle wird ein Eingangs-Signal empfangen,
• – das Eingangs-Signal wird von der aktiven Schnittstelle an eine intelligente Einheit geleitet,
• – von der intelligenten Einheit wird geprüft, ob es sich bei dem Eingangs-Signal um das Aktivierungs-Signal handelt,
• – für den Fall, dass es sich bei dem Eingangs-Signal um das Aktivierungs-Signal handelt, wird die zumindest eine inaktive Schnittstelle aktiviert.

Durch das erfindungsgemäße Verfahren wird es somit ermöglicht, eine inaktive Schnittstelle über eine aktive Schnittstelle (im simpelsten Fall die Spannungsversorgung) zu aktivieren. Es entfällt somit die Notwendigkeit eines HMI‘s am Feldgerät.The invention solves this problem by a method for activating at least one inactive interface of a field device of process automation by means of an activation signal. The method comprises the following method steps:

• - An input signal is received at an active interface,
• The input signal is passed from the active interface to an intelligent unit,
• The intelligent unit checks whether the input signal is the activation signal,
• In the event that the input signal is the activation signal, the at least one inactive interface is activated.

The inventive method thus makes it possible, an inactive interface via an active interface (in the simplest case, the Power supply). This eliminates the need for an HMI on the field device.

The method can be developed in various variants.

• – Ab dem Zeitpunkt der Aktivierung der zumindest einen Schnittstelle wird eine Zeitstoppung begonnen,
• – innerhalb eines vordefinierten Zeitfensters nach Beginn der Zeitstoppung wird an der zumindest einen Schnittstelle ein zweites Eingangs-Signal empfangen,
• – das zweite Eingangs-Signal wird von der zumindest einen Schnittstelle an die intelligente Einheit geleitet,
• – von der intelligenten Einheit wird geprüft, ob es sich bei dem zweiten Eingangs-Signal um ein zweites Aktivierungs-Signal handelt,
• – für den Fall, dass es sich bei dem zweiten Eingangs-Signal nicht um das zweite Aktivierungs-Signal handelt, wird die zumindest eine Schnittstelle nach Ablauf des Zeitfensters (t_i–t₀) deaktiviert.

Bei dieser Weiterbildung wird dadurch, dass über die zu aktivierende Schnittstelle ein zusätzliches Aktivierungs-Signal generiert werden muss, eine zusätzliche Sicherheitsfunktion durch Verifikation bereitgestellt.In a first development, the method comprises the following further method steps:

• From the moment of activation of the at least one interface, a time-out is started,
• Within a predefined time window after the start of the time-out, a second input signal is received at the at least one interface,
• The second input signal is passed from the at least one interface to the intelligent unit,
• The intelligent unit checks whether the second input signal is a second activation signal,
• - In the event that the second input signal is not the second activation signal, the at least one interface is deactivated after the time window (t _i -t ₀ ) has expired.

In this development, an additional safety function is provided by verification that an additional activation signal must be generated via the interface to be activated.

• – Ab dem Zeitpunkt der Aktivierung der zumindest einen Schnittstelle wird eine Zeitstoppung begonnen,
• – nach Ablauf eines vordefinierten zweiten Zeitfensters nach Beginn der Zeitstoppung wird die zumindest eine Schnittstelle wieder deaktiviert.

Auch diese Weiterbildung erhöht die Zugriffs-Sicherheit über die aktivierte Schnittstelle dadurch, dass die Aktivierung nur temporär erfolgt.In an alternative development, the method comprises the following further method steps:

• From the moment of activation of the at least one interface, a time-out is started,
• - After expiration of a predefined second time window after the beginning of the time-out the at least one interface is deactivated again.

This development also increases the access security via the activated interface in that the activation takes place only temporarily.

In a particularly simple executable embodiment variant, the activation signal is generated by manually applying a supply voltage in a sequence of time-predefined time intervals. In this case, therefore, no higher-level unit for generating the activation signal must be provided.

Alternatively, the activation signal can be generated by a higher-level unit. If this is the case, it is advantageous if the activation signal is encoded in a protocol suitable for unit signals, such as "HART" or "Foundation Fieldbus".

• – Eine Sensor-/Aktor-Einheit zur Erfassung und/oder zur Beeinflussung von Prozessvariablen,
• – zumindest eine inaktive Schnittstelle,
• – eine aktive Schnittstelle, zum Empfangen eines Aktivierungs-Signals, wobei eine übergeordnete Einheit vorgesehen ist, die zum Senden des Aktivierungs-Signals und/oder zur Energieversorgung des Feldgeräts mit der aktiven Schnittstelle verbunden ist,
• – eine intelligente Einheit zur Erkennung des Aktivierungs-Signals, zur Aktivierung der inaktiven Schnittstelle bei Erkennung des Aktivierungs-Signals und/oder zur Steuerung der Sensor-/Aktor-Einheit.

Furthermore, the object on which the invention is based is achieved by a field device for carrying out the method described in one of the preceding claims, comprising:

• A sensor / actuator unit for detecting and / or influencing process variables,
• At least one inactive interface,
• An active interface, for receiving an activation signal, wherein a higher-order unit is provided which is connected to the active interface for transmitting the activation signal and / or for powering the field device,
• - an intelligent unit for detecting the activation signal, for activating the inactive interface upon detection of the activation signal and / or for controlling the sensor / actuator unit.

In an advantageous form of the field device, the active interface is designed such that it is suitable for processing unit signals, in particular 4-20 mA signals or 0-10 V signals.

An inventive form of embodiment of the field device based thereon provides that the active interface is a 4-20 mA interface, the inactive interface being based on a "HART" based interface, and wherein FIG -20 mA interface and the HART interface is the same physical interface. In an alternative embodiment variant of the field device, the at least one inactive interface is a wireless interface, in particular a Bluetooth interface or a wireless HART interface.

The invention will be explained with reference to the following figures. It shows:

1 : a field device 1 with an inactive interface 3 ,

2 an activation signal S _a , in the form of a sequentially Q applied supply voltage U _V.

1 shows a field device 1 with an inactive interface 3 , The field device has a sensor / actuator unit 6 for recording process variables and / or for controlling process parameters.

The inactive interface 3 In the exemplary embodiment shown, it is designed as a wireless interface, so that wireless signals can be received, processed and sent in accordance with corresponding standards such as, for example, Bluetooth. The activation of the inactive interface 3 is going through an intelligent unit 5 , For example, a microcontroller, controlled, whereby it is ready to receive or receive. Likewise, through the intelligent unit 5 a new deactivation of the interface 3 be effected.

The inactive interface 3 is through the intelligent unit 5 activated once the smart unit 5 a predefined activation signal S _a recognizes. The activation signal S _a becomes the intelligent unit 5 according to the invention via an active interface 2 fed. Depending on the execution of the active interface 2 the activation signal S _a different character can possess.

The active interface 2 is in the in 1 shown embodiment via a wired connection with a parent unit 4 which may be a process control center or the like connected. The active interface 2 can take on different tasks depending on the type of implementation. When designing the active interface 2 as a 2-wire cable with the corresponding transmission standard, such as "HART" or "Profibus", it can be used by the sensor / actuator unit 6 determined measured value, for example, as a unit signal, preferably 4-20 mA signal transmit. At the same time, in this design via the active interface 2 Data transfer by means of the appropriate protocol between the intelligent unit 5 and the parent unit 4 be performed. Since transmission protocols such as "HART" are based on unit signals such as 4-20 mA or 0-10 V, the field device can 1 over the active interface 2 also optionally be supplied with the necessary supply voltage U _V for operation. With such a corresponding configuration of the active interface 2 There are several ways to define the activation signal S _a .

A first possibility is to define the activation signal S _A in accordance with a 2-wire-compliant standard as "Profibus" or "hard". In this case, the activation signal S _a by the parent unit 4 generated and according to the appropriate standard to the intelligent unit 5 directed.

• – Eine erstes Zeitintervall t₁, in dem die Versorgungsspannung U_V angelegt wird,
• – eine darauf folgenden Periode, in der das Feldgerät nicht an der Versorgungsspannung angeschlossen ist,
• – ein nachfolgendes, längeres Zeitintervall t₂ bei angelegter Versorgungsspannung U_V, und
• – eine zweite Periode bei abgeschalteter Versorgungsspannung U_V, bevor die Versorgungsspannung U_V dauerhaft angelegt wird.

Es versteht sich von selbst, dass die Sequenz Q auch beliebig anders definiert sein kann.A second possibility for defining the activation signal S _a is to apply a supply voltage U _V in a predefined sequence Q. One possible definition of such a sequence Q is in 2 shown schematically. In the case shown, the sequence Q consists of four sections:

• A first time interval t ₁ in which the supply voltage U _{V is} applied,
• - a subsequent period in which the field device is not connected to the supply voltage,
• - A subsequent, longer time interval t ₂ with applied supply voltage U _V , and
• - A second period with disconnected supply voltage U _V , before the supply voltage U _{V is applied} permanently.

It goes without saying that the sequence Q can also be defined in any other way.

In that embodiment variant of the inventive method in which the supply voltage U _{V is applied} in a predefined sequence Q, the parent unit 4 consist only of one voltage source. In this case, a so-called "Pre-power Fail" circuit, which is present in many field device types, must be in the affected field device 1 be installed. Such a circuit ensures that input data transmitted to the intelligent unit is stored in the event of a power failure before the field device 1 loses its functionality. Thus, it is ensured that the sequence Q, despite intermittent periods with disconnected supply voltage from the intelligent unit 4 is recognized.

If there is no pre-power fail circuit, there is alternatively the possibility of using a counter circuit and a nonvolatile memory to detect whether the supply voltage U _{V has been applied} in a predefined sequence Q. In such an embodiment variant, the counter circuit counts directly after Applying the supply voltage U _V, for example, in the second cycle high and writes at each new application of the supply voltage U _V the accumulating counter value in a non-volatile memory. Furthermore, every time the supply voltage is applied again, the written counter value is read out, thereby detecting the elapsed time before the last power interruption. In this case, suitable measures for redundant storage of this count must be taken because the switch-off could take place during a write operation in the non-volatile memory.

LIST OF REFERENCE NUMBERS

1

 field device

2

 Active interface

3

 Inactive interface

4

 Parent unit

5

 Smart unit

6

 Sensor / actuator unit

Q

 sequence

S _a

 Enable signal

t _i

 time interval

U _V

 Supply voltage

Claims (10)

Method for activating at least one inactive interface ( 3 ) of a field device ( 1 ) of the process automation by means of an activation signal (S _a ), comprising the following method steps: - at an active interface ( 2 ) an input signal is received, - the input signal is received from the active interface ( 2 ) to an intelligent unit ( 5 ), - of the intelligent unit ( 5 ) is checked whether it is the input signal to the activation signal (S _a ), - in the event that it is the input signal to the activation signal (S _a ), the at least an inactive interface ( 3 ) is activated. Method according to Claim 1, comprising the following further method steps: - From the point in time (t ₀ ) of activating the at least one interface ( 3 ) a time stop is started, - within a predefined time window after the start of the time stop (t _i -t ₀ ), at the at least one interface ( 3 ) receive a second input signal, - the second input signal is from the at least one interface ( 3 ) to the intelligent unit ( 5 ), - of the intelligent unit ( 5 ) it is checked whether the second input signal is a second activation signal (S _a2 ), - in the event that the second input signal is not the second activation signal (S _a2 ) the at least one interface ( 3 ) is deactivated after expiration of the time window (t _i -t ₀ ). Method according to Claim 1, comprising the following further method steps: - From the point in time (t ₀ ) of activating the at least one interface ( 3 ), a time stop is started, - after expiration of a predefined second time window after the beginning of the time stop (t _j -t ₀ ), the at least one interface ( 3 ) deactivated again. The method of claim 1, 2 or 3, wherein the activation signal (S _a ) by manually applying a supply voltage (U _V ) in a sequence (Q) from temporally predefined time intervals (t _i ) is generated. Method according to one of the preceding claims, wherein the activation signal (S _a ) by a higher-level unit ( 4 ) is produced. The method of claim 5, wherein the activation signal (S _a ) is encoded in a protocol suitable for unit signals. Field device for carrying out the method described in one of the preceding claims, comprising: a sensor / actuator unit ( 6 ) for the detection and / or influencing of process variables, - at least one inactive interface ( 3 ), - an active interface ( 2 ), for receiving an activation signal (S _a ), wherein a higher-level unit ( 4 ) is provided, for transmitting the activation signal (S _a ) and / or for supplying power to the field device ( 1 ) with the active interface ( 2 ), - an intelligent unit ( 5 ) for detecting the activation signal (S _a ), for activating the inactive interface upon detection of the activation signal (S _a ) and / or for controlling the sensor / actuator unit ( 6 ). Field device according to claim 7, wherein the active interface ( 2 ) is designed such that it is suitable for processing unit signals. Field device according to claim 8, wherein the active interface ( 2 ) is a 4-20 mA interface, with the inactive interface ( 3 ) is a HART interface, and where the 4-20 mA interface and the HART interface are the same physical interface. Field device according to at least one of claims 5 to 8, wherein the at least one inactive interface ( 3 ) is a wireless interface, in particular a Bluetooth interface or a wireless HART interface acts.

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