FI126027B - Method and apparatus for dynamically configuring an industrial control system - Google Patents

Description

METHOD AND APPARATUS FOR DYNAMIC CONFIGURATION OF AN INDUSTRIAF CONTROF SYSTEM

Technical field

Generally, the invention relates to industrial control systems, such as supervisory control and data acquisition (SCADA) systems, used in a variety of utility markets, such as power generation and distribution. The invention relates to bidirectional communication of data and control signals between field devices, controlling devices and monitoring devices using various types of communication networks.

Background technology

Electricity distribution networks are remotely controlled and monitored for example by supervisory control and data acquisition (SCADA) systems. In general, these systems employ a number of field devices (e.g. remote terminals, RTU), communication networks (e.g. radio modems, packet-switched radio networks, fiber optic networks, satellite communications), telecontrol protocols (e.g. IEC 60870-5-104, IEC 60870-5-101, DNP-TCP), protocol front-end processors and human-machine interfaces (HMI).

The front-end processor handles the telecontrol protocol communication between itself and the field devices. The HMI application queries and controls the front-end processor by using typically some higher-level protocol like remote database access. The front-end and HMI functionality may be combined to single unit, especially on small systems.

Existing systems are optimized for communicating with higher-level field devices, such as electricity substations and typically utilize fiber optic or other fixed type communication links. However, increasing degree of network automation demands for more field devices in the form of lower-level field devices such as RTU’s on pole-top disconnectors. It is not technically and economically feasible to employ fixed link networks in conjunction with these lower-level field devices because of the large quantity and wide locational spread of these devices whereas radio networks offer a better solution for their communication network implementation.

The various network types have different transmission properties and requirements towards the system employing said type of network. Fiber optic or other fixed-type networks typically have small and constant round-trip delays with virtually no packet loss or connection breakups whereas radio networks (e.g. GPRS, 3G, 4G, satellite) present longer and non-constant round-trip delays in addition to higher rates of packet-loss and connection breakups.

The aforementioned network type related properties and differences between them require network specific settings on the telecontrol protocol level. For example settings for handling timeouts in fiber optic and wireless communication networks differ profoundly and are not suitable to be used interchangeably.

Technically it is possible to modify settings per connection type, but this presents many additional problems as this requires altering the existing system and separate settings causing extra maintenance work. Internal policies do sometimes not allow this kind of modifications but do require the standard protocol settings to be used. In some front-ends it is not even possible to define separate parameters per connection type so that common settings for all connections are used.

Radio networks per se exhibit timely short duration connection drops and an assumed loss of connection within the control system is treated as a major fault in the existing system designs and may cause a request of personnel attendance on site. To overcome the problem of unnecessary alerts due to network specific properties, using common telecontrol settings for all connection types means that the protocol timeouts are adjusted to the worst-case situation defined by the radio network. This however slows down the high-priority communication from the fixed-line electricity substations.

Further, it is possible to use a separate front-end for the wireless connections and thus the HMI shares two or more network front-ends. Typically a separate network front-end with adapted protocol settings is used for radio network connected devices. This solution increases the cost and complexity of the system and causes significant delays for building a proof-of-concept system.

One further existing solution is to use a protocol conversion gateway between the front-end and the radio networks. A single front-end with standard settings can be used. The connections from the front-end are terminated to the protocol conversion gateway. The protocol conversion gateway maintains separate connections to the field devices and can therefore use radio network adapted telecontrol protocol set tings towards the field devices and the standard protocol settings toward the front-end. However, this requires configuration and maintenance work as in conventional protocol conversion gateways each data-point of the field devices needs to be predefined to the database of the protocol conversion gateway. These settings typically include the data object type, object address toward field devices, object address toward the front-end, required message types and actions. In larger systems the initial configuration work can be significant and error-prone. Similarly every change in the field system needs to be re-defined to the protocol gateway.

Summary of the invention

It is an object of the present invention to implement such a solution, that previously mentioned drawbacks of the prior art could be diminished. In particular, the invention is implied to solve the drawbacks regarding building and maintaining an industrial control system allowing the use of different types of field devices and network types and changes in the system during its lifetime to be dynamically configured into a preferred control system using a device, method and computer program product disclosed here, the device referred herein as an adapter.

The objective of the invention is met by the features disclosed in the independent patent claims.

The apparatus according to the present invention is characterized by the features of claim 1. The method according to the present invention is characterized by the features in the independent patent claim 10. The computer program product according to the present invention is characterized by the features in the independent patent claim 15.

Some preferable embodiments of the invention are described in the dependent claims.

Significant advantages can be achieved with the present invention when compared to the prior art solutions. Separate connections are used between the front-end and the adapter and between the adapter and the field devices. This allows using the existing front-end telecontrol protocol settings as is.

To overcome the drawback of having to pre-define each data-point of the field devices as when using a protocol conversion gateway between the front-end and the field devices as known from prior art, the invention discloses a device, method and computer program product, the device referred herein as an adapter, that dynamically builds up the object database therefore eliminating the manual configuration and maintenance work.

Short description of the drawings

Next, the invention is described in more detail with reference to the appended drawings, in which

Fig. 1 is a block schematic diagram showing a simplified overall layout of an industrial control system employing the adapter of the present invention for one embodiment of the invention.

Fig. 2 illustrates a simplified overall flow chart description of one embodiment of the method of the present invention.

Fig. 3 is a signaling chart illustrating one embodiment of a connection establishment by the adapter of the present invention.

Fig. 4 is a signaling chart illustrating one embodiment of closing of a connection by the adapter of the present invention.

Fig. 5 is a signaling chart illustrating one embodiment of the principle of using separate timers for different connections according to the present invention.

Fig. 6 is a signaling chart illustrating one embodiment of the principle of automatic learning of monitored data points by the adapter of the present invention.

Fig. 7 is a signaling chart illustrating one embodiment of the operation of the adapter of the present invention in a situation where a connection to a controlled station is permanently lost.

Fig. 8 is a signaling chart illustrating one embodiment of the operation of the adapter of the present invention in a situation where a connection to a controlled station is temporarily lost.

Fig. 9 is a signaling chart illustrating one embodiment of the handling of a long delay on the remote communication link by the adapter of the present invention.

Detailed description of the embodiments

Described below is the device for dynamic configuration of an industrial control system referred herein as an adapter and the method and computer program product to achieve the same. Dynamic configuration of an industrial control system refers in particular to configuration of each data-point of the field devices to the database of the adapter during the entire lifetime of the system including the setup and in-use changes of the system and its components.

Electricity distribution networks are remotely controlled and monitored for example by supervisory control and data acquisition (SCADA) systems where the described device, method and computer program product finds particular use. FIG. 1 illustrates a simplified overall layout of one such industrial control system 1 employing the adapter 6 of the present invention. In general, these systems employ a number of field devices such as higher-level field devices, such as electricity substations 4 or lower-level devices 5 (e.g. remote terminals, RTU), communication networks or links 7, 8, 9, 10 (e.g. radio modems, packet-switched radio networks, fiber optic networks, satellite communications) with appropriate protocols, protocol front-end processors 2 and human-machine interfaces 3 (HMI).

The field devices may be any form of devices that are commonly monitored and/or controlled by an industrial control system, such as a SCADA system. The present invention does not necessarily concern the design of such devices. Rather, the present invention is primarily directed to a communication device, method and computer program product that acts as an interface and middleware between a said front-end and a number of said field devices.

A presently preferable embodiment of the device, method and computer program product realizing dynamic configuration of an industrial control system according to the present invention will be described next. This description is not meant to limit the scope of the invention. Persons of ordinary skill in the art may recognize equivalent constituting elements of the method, computer program product or device that can be substituted for those described herein to achieve the same effect. The reader is advised and reminded that the use of such equivalents is deemed to be within the scope of the present invention.

The adapter 6 has first communication means 100 for establishing a connection between itself and the front-end 2 adapted to communicate according to the utilized network or link 9 and front-end telecontrol protocol. Further, the adapter has second communication means 101 for establishing a connection between itself and the field devices 4, 5 adapted to communicate according to the utilized network 7, 8 type and corresponding telecontrol protocol. The adapter 6 is equipped with means for data storage 103 for adapter maintained local storage of, for example, data-points of the field devices, typically including the data object type, object address toward field devices, object address toward the front-end, required message types and actions etc. The adapter is equipped with processing means 102 capable of performing the tasks according to the method of the present invention and running the computer program product executing said method.

FIG. 2 illustrates a simplified overall flow chart description of one embodiment of the adapter apparatus and method of the present invention in the presence of front-end and field devices. When the front-end makes a request 11 to the adapter the adapter checks 14, 15 whether it already haves the data and serves 18 the requested values from the local data storage. If the requested data-point is not known to the adapter it makes a new query 17 to the field device. If the field device answers 21 to the query the adapter stores 25 this new data-point to its local data storage and dynamically adds 22 it to the list of the data-points it is monitoring along with the configuration information of the data point. Otherwise the adapter informs 24, that the data point is not available. The stored information includes the protocol address, object type and other object properties e.g. the general interrogation group it belongs to. The requested data is transferred to the requesting front-end as it is stored 25.

The adapter can also dynamically alter the policies regarding how often the data-point update is requested from the field devices. If the value of the data-point is requested only occasionally by the front-end, the adapter may ask the update from the field device only when required 11. If the data-point is requested often by the front-end the adapter may start 13 independently to update 16 the value from the field devices. This reduces the amount of communication required on the radio network and reduces the response time toward the front-end for important data-points. Similarly the adapter may drop the data-point from the internal query list when the front-end reduces the amount of queries to the data-point.

The adapter can detect whether the field-device either asynchronously 12 or synchronously 12, 13 reports the value of the data-point. Asynchronous reporting is typically used by telecontrol protocols when the value of the data-point changes. Asynchronous reporting of a new 19 data point is followed by adding 22 dynami cally the new data point to the data base of the adapter and transmitting 25 the value, if required by the system. Synchronous reporting is typically used as a backup to make sure fresh values are available. In these cases the adapter may reduce its internal query frequency for the affected data-points therefore reducing the amount of radio communication.

In case of communication failure (“connection drop”) 20 between the adapter and the field device, the adapter may serve the front-end from the internal data storage while initiating a reconnect 23 until new connection is established. This can be used for hiding the occasional short duration connection drops from the front end and therefore reduce the amount of false alarms.

FIG. 3 to FIG. 9 will further illustrate the operation of one embodiment of the adapter apparatus and method of the present invention with clarifying examples. For illustrative purposes a signaling chart with notation similar to the descriptive convention of the IEC 60870-5-104 standard is used to explain the operation and signaling of the described adapter in connection with the controlling station and controlled station of an industrial control system. The representation and notation is not meant to be restrictive but as one possible alternative to illustrate the intended way of operation of the device and the method to achieve the same according to the present invention.

FIG. 3 illustrates a successful telecontrol protocol (TCP) connection establishment procedure where the controlling station makes a connection request 30 for a controlled station not configured in the adapter. The adapter stores the destination IP and Port combination to its local database and starts the connection process 31 towards the controlled station. Timers tO 32 and TO 33 specify the connection establishment timeouts of the controlling station and the adapter, respectively. When timeout tO 34 is reached the controlling station sends a new connection request to the adapter. The destination IP and Port combination is now known already and the connection process is already active. When timeout TO 35 is reached again the adapter makes a new request towards the intended controlled station. As an example, when TO is reached again without a successful reply from the controlled station, the adapter dynamically increases the timeout TO 36 to allow for the slower remote communication connection. After the adapter receives a request acknowledgement 37 from the controlled station it signals the acknowledgement 38 towards the controlling station and control station establishing the new connection 39.

FIG. 4 illustrates one example of the way the adapter can dynamically alter the policies regarding how often the data points are updated depending on how or how often the data point is requested. In FIG. 4 controlling station signals 40 to close the connection to the controlled station. During a timeout period T4 41 the adapter keeps the connection open towards the controlled station and stores the data it receives asynchronously from the controlled station and continues to acknowledge the controlled station within specified timeout T2 42 after receiving the latest frame and performs a link test as required by a set interval T3 43. When T4 is reached 44 the adapter regards the controlled station as temporarily not needed and it starts connection closing signaling 45 towards said station but keeps the respective stored data in its local database. When there is no further activity from the controlling station to the controlled station and timeout T5 46 is reached the adapter deems the controlled station as permanently not needed and removes all respective data of the controlled station from the local database of the adapter.

FIG. 5 further illustrates the use of different timers according to the present invention. One significant advantage of the present invention is the use of separate timers between the controlling station and the adapter and between the adapter and the controlled station allowing among other things the adaptation between different types of connections. Timers tl 50 and T1 51 are timeouts for waiting link-level acknowledgement from the recipient after sending the latest frame of the controlling station and the adapter, respectively. Timers t2 52 and T2 53 are timeouts for sending link-level acknowledgement to the sender after receiving the latest frame of the controlling station and the adapter, respectively. Following an application command 54 from the controlling station the adapter does not receive an acknowledgement from the controlled station within the specified timeout t2 52. To prevent the controlling station from reaching the timeout tl 50 and thus terminating the connection, the adapter sends a separate link-level acknowledgement 55 to the controlling station and after the adapter receives the controlled station acknowledgement 56 (within the specified interval Tl 51) the adapter sends an application level confirmation 57 to the controlling station and an acknowledgement to the controlled station within the specified interval T2 53.

FIG. 5 further shows an example of one embodiment of the link testing procedure according to the present invention. Separate timers t3 58 and T3 59 are used for the controlling station and the adapter for timeouts for testing an idle link. The adapter acts as an interface acknowledging the controlling station of a working local communication link which is tested by the controlling station after an idle interval t3 58 and similarly the adapter testing the remote communication link towards the controlled station after an idle interval T3 59.

FIG. 6 illustrates an example how by monitoring the general interrogation data flow the adapter can learn the monitored data points. This learning can be utilized by the adapter, if the remote communication link is temporarily unavailable or there is a need to minimize the amount of remote communication. The adapter can answer some additional general interrogation request locally from its database. In FIG. 6 the controlling station issues a general interrogation 60 of the monitored information. The adapter sends a query 61 to the controlled station and receives 62 the monitored information object addresses (IOA), type identifications (TI), qualifier of interrogation (interrogation group identifier QOI) and object values. The adapter stores 63 this information to the general interrogation (GI) table and supplies 64 the controlling station with the monitored information. When the adapter receives update information from the controlled station, it updates 65 the GI table, when the IOA belongs to the table. When the GI table does not contain the supplied IOA, the data is stored 66 to an asynchronous data table. When a general interrogation request (TI=100) with the earlier QOI is received 67 by the adapter it supplies 68 the monitored data points locally from the GI table stored in the database of the adapter.

FIG. 7 further describes the use of the GI table in an example, where the TCP connection is permanently lost between the adapter and the controlled station. In the example of FIG. 7 the adapter serves 71 the controlling station link test requests 70 and transmits 73 according to data query request 72 (general interrogation, read request) from the local database of the adapter according to the timers specified in earlier examples. After a timeout Tl 74 the adapter starts a reconnect attempt towards the controlled station. After it receives a GI request 72 from the controlling station, it supplies 73 the monitored data points from its local database GI table until a timeout interval T7 75 is reached without a successful reconnect with the controlled station. The adapter deems the controlled station permanently unavailable and closes the corresponding connection towards the controlling station and deletes all stored data corresponding to the controlled station. A separate timeout T6 (T6 < T7) may be used to define when the stored data objects are marked to contain invalid data.

FIG. 8 describes the use of the GI table in an example, where the TCP connection is temporarily lost 80 between the adapter and the controlled station. As in the previous example of FIG. 7 the adapter serves 82 the controlling station link test requests 81 and transmits 84 according to data query request 83 (general interrogation, read request) from the local database of the adapter according to the timers specified in earlier examples. The connection to the controlled station is re-established 85 before the timeout interval T7 86 is reached and the next GI request 87 by the controlling station is processed 88 transparently (not locally from the adapters database) in order to refresh all data.

The example of FIG. 9 further describes a situation where there is a long delay on the remote communication link. The remote communication link is available 90 and when the controlling station sends a GI request 91 the adapter processes 92 the request transparently even though the local database contains the interrogated values at the adapter. The long delay on the remote communication link causes a timer value T8 93 to be exceeded before the controlled station confirms the interrogation request and the adapter serves 94 the controlling station from its local database GI table. The value of T8 is so defined that the application level timeout tl 95 of the controlling station is not reached before the adapter confirmation 96 the interrogation request has reached the controlling station. Thus the long delay of the remote communication link does not disturb the continuity of the systems operation.

The scope of the invention is determined by the attached claims together with the equivalents thereof. The skilled persons will again appreciate the fact that the explicitly disclosed embodiments were constructed for illustrative purposes only, and the scope will cover further embodiments, embodiment combinations and equivalents that better suit each particular use case of the invention.

Claims (15)

In an industrial device network for interconnecting devices (2,4,5), apparatus (6) adapted to transmit data and / or control signals between a control device (2) and a plurality of controlled devices (2,4,5) having data points. , which enables dynamic configuration of interconnection of said devices in hardware (6) with a database, comprising configuration of data points in a database, and further comprising first communication means (100) for connecting hardware (6) to control device (2) for transferring data and / or control signals 2) and between said apparatus (6), said means being configurable to communicate using one or more assigned communication networks and / or links and a communication protocol; second communication means (101), which may not be identical to said first communication means (100), for connecting an apparatus (6) to a plurality of controlled devices (4,5) for transmitting data and / or control signals between said devices (4,5) and said apparatus (6) ) wherein said means (100,101) is configured to communicate using one or more assigned communication networks and / or links and a communication protocol; wherein said apparatus (6) is characterized in that it has processing means (102) which are programmable to dynamically configure said interconnections by using programmed rules and said data and said control signals and timers defined by values representative of time intervals, said values being adjustable said processing means (102); data storage means (103) for storing and retrieving data and configuration information representing said interconnections and changes in said data and said configuration information, said data and configuration information and changes thereto being retrieved using said first communication means (100) and / or second communication means (100); and / or processed using said processing means (102) and / or transmitted using said communication means (100,101). The apparatus (6) of claim 1, wherein the system associated with said industrial equipment network is an industrial control system, such as a Supervisory Control and Data Acquisition (SCADA) system. The apparatus (6) of claim 2, wherein said controlling device (2) is a front end of said SCADA system. The apparatus (6) of claim 2, wherein said controlled device (4,5) is a field device used by said SCADA system, such as a substation or a remote station. Apparatus (6) according to claim 1, wherein said first and / or second communication means (100,101) include an interface port or wireless interface such as GPRS, EDGE, 3G, 4G, LTE, CDMA, WiMAX, polling the radio and / or the microwave were received by / 1. The apparatus (6) of claim 1, wherein said communication networks include radio modems, packet switched radio networks, fiber optic networks, and satellite communications. The apparatus (6) of claim 1, wherein said communication protocols include IEC-60870-5-104, IEC-60870-5-103, IEC-60870-5-101, IEC 61850, and IEEE 1815-2010 (DNP3). The apparatus (6) of claim 1, wherein said timers include a communication protocol time limit for specifying timeout slots for connection set-up, link-level acknowledgment waiting, link-level acknowledgment transmission, free-link testing, link temporary loss estimation, link loss estimation, and / or timers derived from said processing means by one or more of said communication protocol time limits. The apparatus (6) of claim 1, wherein said configuration information includes a data object type, protocol address, object addresses per field device, object addresses per front end, required message types and actions, and general data interrogation groups. A method for dynamically configuring a control device (2) and a plurality of controlled devices (4,5) having data points in a database-equipped hardware (6) operating at an interface between said devices (4,5) and comprising configuring the data points in a database. said method further comprising the step of providing a network through which a control device (2) as its industrial control system and a plurality of controlled devices (4,5) can selectively communicate with each other through said interface; characterized in that the method defines communication at said interface with one or more of said devices (4,5) using programmed rules and data and / or control signals (40) received from one or more of said devices (2,4,5), and timers defined by values representing time slots; defining configuration information associated with said interconnections identified by said selective communication of said devices (2,4,5) and / or said defined communication generated between an interface and one or more of said devices, using said network. The method of claim 10, wherein said defined communication at said interface includes requesting data points and transmitting data received from or retrieved from one or more of said devices (2,4,5) from a local database. The method of claim 10, further comprising deciding whether or not the request-related data is provided transparently by requesting said data from one or more devices of said system or locally retrieving said data from a local database, said decision being determined by the value of one or more of said timers. . The method of claim 10, further comprising adjusting the time interval between successive requests for updating the value of said data points according to how often the devices of said system request said value and / or whether the device providing said value uses a synchronous or asynchronous data reporting procedure ( 12,13). The method of claim 10, wherein determining said configuration information includes monitoring said selective communication and said defined communication, and storing information representing said data points locally in a database, wherein the information typically includes a data object type, protocol address, object address per field device, request object, A computer program product comprising a computer-readable medium implemented with a computer-readable code controlling device (2) and a plurality of controlled devices (4,5) having data points to enable dynamic configuration of interconnections of said devices (4) with a database. 5) in an interface operating hardware (6) comprising configuring data points in a database, said computer program code further comprising instructions for a network through which an industrial control system control device (2) and a plurality of controlled devices (4,5) can selectively communicate with said interface. through, forming; communication at said interface for defining one or more of said devices using programmed rules and data and / or control signals received from one or more of said devices, and timers defined by values representing time slots; defining configuration information associated with said interfaces, which is identified by said selective communication of said devices and / or said defined communication generated between an interface and one or more of said devices, using said network.