Note: Descriptions are shown in the official language in which they were submitted.
CA 02454968 2004-01-23
METHOD FOR DATA EXCHANGE BETWEEN AN OPERATING AND MONITORING
PROGRAM AND A FIELD DEVICE
The invention relates to a method for a data exchange
between an operating and monitoring program and a field device,
which is connected with the internet via a field bus adapter.
In process control technology, field devices are often used
for detecting and affecting process values.
Examples of field devices are temperature measuring
devices, which detect the temperature of a process medium, flow
meters, which detect the flow of a process medium through a
section of a pipeline, or fill indicators, which determine the
fill level of a fluid or of bulk material in a container.
Process control is performed from a control system which is
connected with the individual field devices via a data bus. All
information required for process control is exchanged between the
control system and the field devices via the data bus.
A data bus which is often employed operates in accordance
2u with the HART standard of the HARTR foundation. Field devices
which operate in accordance with the HART standard are also called
HART devices.
Besides this, Profibus(R) or Foundation Fieldbus(R), inter
alia, are often employed as field buses in process automation
technology.
Besides the straight transmission of measured values, field
devices also permit the transmission_.of different information
stored in the field device, for example parameters (zero point,
measured value capacity, etc.), calibration curves, as well as
1
CA 02454968 2008-07-07
79171-9
diagnostic information. The parameters can be set from the
control system or from an operating and display device.
This process is also called configuration and
parameterization of the field device.
The field device must be configured and parameterized prior
to each first use or after a device change.
The operating and monitoring programs mostly run on
computer units (PCs, laptops), which are connected via a serial
COM interface (for example RS232, RS485) with a field bus adapter
connected to a field bus.
Commercially available operating and monitoring programs
are, for example, CommuWin of the Endress + Hauser-Maulburg, or
ReadWin of the Endress + Hauser Wetzer, companies.
The disadvantage of these standard application programs
lies in that they can only be used in the immediate vicinity of
the field bus, since a cable connection between the computer unit
and the field bus adapter is necessary. A data exchange over
greater distances (worldwide in the extreme case) is theretore not
possible.
In principle, standard application programs can be
rewritten in such a way that they access the field devices via an
internet interface. However, this requires a considerable
programming outlay and extensive adaptations.
Application programs for control systems are furthermore
known, which access the internet via an internet interface and
establish the connection with the field buses via appropriate
gateways. Worldwide access to field devices becomes possible by
means of this.
In most cases, application programs for control systems are
voluminous and expensive.
The object of some embodiments of the invention is
based on creating a method
2
CA 02454968 2008-07-07
. .f - .
79171-9
for data exchange between an operating and monitoring program and
a field device which, by simple means and with the use of standard
application programs, makes possible the access to field devices
over extended distances via the internet.
In some embodiments, this object is attained by means of a
method for data exchange between an operating and monitoring program
and a field device which is connected to the internet by mean s of a
field bus adapter, and is distinguished in that the operating and
monitoring program accesses a serial interface which is connected
with an internet interf ace .
In some embodiments, the operating and monitoring
device furthermore accesses a serial
interface. Therefore the operating and monitoring devices does
not "realize" that the connection to the field device.does not
take place via an RS232 connection, but via the internet.
Advantaqeous further developments of the irlvention are
recited in the dependent claims.
In accordance with a first embodiment of the invention, the
connection between the operating and application program and the
internet interface takes place via a first COM interface, a zero
modem cable and asecond COM interface.
Here, the connection takes place via two physically present
.interfaces, for example COM1 and COM2 of the computer unit on
which the operating and monitoring program runs.
This application only requires an appropriate driver for
the internet interface which performs the program conversion and
manages the addresses of the field bus adapters.
In accordance with a second embodiment of the invention,
the connection between the operating and application program and
the internet interface takes place via a virtual serial interface.
Although this design requires aslightly greater
programming outlay, it can also be used in connection with
computer units, in particular laptops, which do not have two
physically present serial interfaces.
3
CA 02454968 2008-07-07
79171-9
According to one aspect of the present invention,
there is provided a method for a data exchange between an
operating and monitoring program BA which is running on a
computing unit and a field device, comprising the steps of:
connecting the field device to the internet via a field bus
adapter; connecting the computing unit with the internet via
an internet interface; providing a connection in the
computer unit between the internet interface and a serial
interface; and the operating and monitoring program BA
accesses the serial interface in a customary manner thereby
exchanging data between the field device and the operating
and monitoring program BA over the internet.
According to another aspect of the present
invention, there is provided a computer unit for exchanging
data between an operating and monitoring program and a field
device, comprising: an internet interface for connecting
the computer unit with the field device via the internet and
a fieldbus adapter; a serial interface which is accessed by
the operating and monitoring program; and a connection
between the serial interface and the internet interface for
transferring data between the operating and monitoring
program and the field device.
3a
CA 02454968 2004-01-23
The invention will be explained in greater detail by means
of the following drawings.
Fig. 1 shows a field bus with a computer unit and several
field devices in a schematic representation,
Fig. 2 shows the computer unit in accordance with a first
embodiment of the invention,
Fig. 3 shows the computer unit in accordance with a second
embodiment of the invention.
A field bus'1.with several field devices 10, 20, 30 is
represented in Fig. 1.
The field'devices 10, 20, 30 are connected with a control
system 4 via'a data bus line 3, or with a computing unit 9 via a
field bixs adapter 5(for'example CommuBox of the Endress + Hauser
company). To this end a connecting line 7 leads from the field
bus adapter 5 to the COM plug conne-ctor 8 of the computer unit 9.
Serial data transmission on the connecting line 7 takes place in
accordance with the RS232 or RS485 ~tandards.
The computer unit 9 is a perAnal computer (PC) or a
portable laptop.
The field bus 1-operates in accordance with known
international standards, such as HARTR, Profibus(R) or Foundation
Fieldbus (R) .
Examples of field devices are, for example, temperature
measuring devices, which detect the temperature of a process
medium, flow meters, which detect the flow through a section of a
pipeline, or fill indicators, which determine the fill level of a
4
CA 02454968 2008-07-07
79171-9
bulk material in a container.
The respective measured values are transmitted to the
control system 4 through the data bus line 3. The control system
=4 controls the entire process course on the basis of the detected
measured values.
Besides straight measured value transmission, intelligent
field devices (smart field devices) allow the transmission of
various information stored in the field device. Thus it is
possible to ball up, or change, various parameters from the
control system 4, or from the computing unit 9. Such parameters
are, for example, the zero point, measured value capacity (range)
or the unit in which the measured value is put out:.
In some embodiments, for example in connection with
till level measuring devices operating in accordance with the echo
principle, to read out echo curves. Conclusions regarding the
ability of the fill level measuring device to function can be
drawn from the echo curve.
In some embodiments, besides this it is also possible to
call up diagnostic information. Some field devices are already
capable of performing a self-diagnosis. This means that defined
core values of the field device are monitored for deviations from
the set values.
Special operating and monitoring programs are used for
displaying this information and changes of the parameters.
These operating and monitoring progra,ms are installed in
the computing unit 9. Customary programs directly access the COM
interface 8 of the computing unit 9.
Fig. 2 shows a computing unit 9 in accordance with a first
embodiment of the invention. Besides a first COM interface 8, the
computing unit 9 has a second COM interface 8a.
The two interface's 8 and 8a are connected with each other
by means of a zero modem cable 11. The computing unit 9'has an internet
interface 13, which is
connected via the internet with a field bus adapter 5 connected to
the field'bus 1.
5
CA 02454968 2008-07-07
79171-9
The operating and monitoring program BA accesses the COM1
interface 8 of the computing unit 9 in the customary manner. The
data connection with the internet interface 13 takes place via the
zero modem cable 11 and the COM2 interface 8a. By means of an
appropriate driver program (bus client), the internet interface 13
sees to the conversion of the data to the TCP/IP standard and, via
a stored address book, to the selection of the appropriate
internet address of the field bus adapter 9'. Data are exchanged
between the computing unit 9 and the field bus adapter 5 via the
internet. The field bus adapter sees to the conversion of the
protocol to the appropriate field bus standard, for example HARTR.
The fact that several different field buses can be-controlled via
the internet interface 13 without mechanical re-plugging can be
cited as a further advantage.
Fig. 3 shows an alternative embodiment of the invention.
Here, the connection between the operating and monitoring program
BA and the internet interface 13 takes place via a virtual
interface V.
This design requires an increased software outlay since it
is necessary to write a software program for the virtual
interface. But the advantage here is that it is also suitable for
computing units 9 which do not have,two COM interfaces, which is
often the case with laptops.
In some embodiments, access via the internet to field devices
21 is made possible by means of
conventional operating and monitoring programs, without elaborate
conversions of the source code of the operating and monitoring
program being necessary: This is of importance mainly when the
source code of the operating and monitoring program is not known
because there is no company-owned program.
6
