WO2007081259A1

WO2007081259A1 - A method and a device for communication over an electric distribution network

Info

Publication number: WO2007081259A1
Application number: PCT/SE2006/001483
Authority: WO
Inventors: Nils-Gunnar Holmer; Stig Wiinberg
Original assignee: Region Skåne
Priority date: 2006-01-13
Filing date: 2006-12-22
Publication date: 2007-07-19
Also published as: EP1977560A1; SE0600054L; SE535835C2

Abstract

Method and device for communication via an electricity distribution network (10) in an establishment, whereby data signals are transmitted via network nodes connected to the electricity distribution network. Information about the physical location of the network nodes (11 ) and a unique identity for each network node (11 ) are stored in a storage unit (17) of a central unit (16) which is connected to the network nodes (11 ; 20). Certain network nodes (11 ) are wirelessly connected to mobile units (13; 14; 15; 27; 28; 29) and communication between the mobile units (13; 14; 15; 27; 28; 29) takes place via network nodes (11 ) and the electricity distribution network (10). Information exchanged between the mobile units (13; 14; 15; 27; 28; 29) is recorded and stored in the central unit (16). The central unit (16) is designed to convey necessary addressing in¬ formation to the network nodes and comprises a storage unit for recording and storing such communication information exchanged between the network nodes. A built-in network node (38) in an appliance (39) communicates with, controls and monitors via units (40-44) a piece of equipment connected to an electricity distribution network.

Description

A METHOD AND A DEVICE FOR COMMUNICATION OVER AN ELECTRIC DISTRIBUTION NETWORK

FIELD OF THE INVENTION

The invention relates to a method and a device for communication via an electricity distribution network, the power supply network. The cables of the electricity distribution network are used for transmitting signals superimposed on the network voltage.

STATE OF THE ART

Power supply network communication, so-called PLC (Power Line Communication) has existed since about 1930. Early PLC systems were analogue and allowed information to be transmitted at the rate of a few kilobits per second (kbit/s). Subsequent digital systems brought somewhat higher capacities.

At the end of the 1990s, systems for high-speed communication via the power supply network were developed with capacities of the order of several Mbit/s. Some of the systems now used in power supply network communication are described below.

Narrow-band PLC operates at relatively low frequencies (3 to 148.5 kHz), usually with a bandwidth of the order of 5 kbit/s. This technique is used primarily for control and monitoring in distributed systems.

Access PLC is a system for high-speed communication via the power supply network and operates in the frequency range 1.6 to 30 MHz, which allows communication with bandwidths of 4 to 20 Mbit/s. A plurality of commercial but mutually incompatible systems of this type is available.

In-house PLC is a system for creating a local data network via the power supply network in a building or property. A plurality of commercial systems is available and compatible under the common designation HomePlug. A current standard caters for capacity of 14 Mbit/s and a future standard for up to 200 Mbit/s.

A system for monitoring a digital security camera is referred to and described in US2004/0155757. The camera and other home electronic appli- ances are connected to one another and to a main unit via an existing power supply network. A modem (modulator/demodulator) connects the appliances and the unit to the power supply network.

The systems available today are based on independent units communicating with one another in small networks or small groups. The organisa- tion and configuration of large networks with reliable monitoring and control involves problems.

In hospital environments and many other similar environments, e.g. local authority care facilities, hotels and manufacturing and trading sites, the laying of cables to rooms for different purposes and functions involves major problems and large costs. When such an environment has to be replanned and the functions of rooms and spaces changed, it is usually necessary to alter the layout of cabling and install new forms of network, causing further costs.

SUMMARY OF THE INVENTION

One object of the invention is to achieve larger and more flexible systems for effective communication within limited areas. A limited area means an establishment comprising one or more buildings. Two or more establishments may cooperate and thereby constitute a limited area.

Another object of the invention is to provide systems for handling and conveying messages and various alarm functions.

A further object of the invention is to provide systems for reliable monitoring of various forms of patient alarms, technical alarms and for transmitting critical information to and from staff in hospital environments. Monitoring of patients can be by control equipment which is connected to the patient and may also make it possible to determine his/her position. Systems executed in accordance with the invention may also be used for controlling and monitoring technical equipment such as fans, dialysis equipment, motors, passage alarms etc.

These objects are achieved by utilising an electricity distribution network existing on site and network nodes connected to it. The network nodes may be provided with suitable means for wireless data communication, e.g. systems based on Bluetooth®, standards within IEEE 802.11 , IEEE 802.16 (WiMax), DECT (Digital European Cordless Telephone), IrDA (Infrared Data Association) and the like. Various types of communicators serve as terminals in the system. A central unit with archive function controls, monitors and conveys communication between terminals and network nodes.

The electricity distribution network is preferably disposed in an establishment comprising a building or a plurality of adjoining buildings. The power supply network is usually of a standard type in different environments and usually remains unchanged even if the function of a location or room changes. Various filters and attenuators are used for limiting communication to a desired area. Various limited areas may be connected together to form larger composite units with two or more central units. The various central units may then cooperate with one another and serve as redundant units. Each individual network node is provided with a unique identity allocated by, or at least known to, the central unit.

It is also possible in this context to utilise the technology known as ADSL (Asymmetric Digital Subscriber Line) for transmitting data on two-wire copper lines. This technology involves superimposing data signals on the electrical voltage signal.

The network nodes may be connected at ordinary wall sockets, in which case they are preferably fastened, e.g. by the screws normally used for fitting the wall socket. Fastening prevents the network nodes being moved unintentionally or erroneously. It is also possible to connect the network nodes permanently to the electricity distribution network. This is done, for example, in roof installations and in installations of a more permanent nature. As an alternative, possibly in combination with the foregoing, the network nodes may be built into electrically connected equipment.

Each room in the building or buildings is preferably provided with at least one network node. Patients in the room have access to or carry an alarm transmitter or alarm unit wirelessly connected to the network node. The alarm transmitter and the alarm unit are associated with a particular patient and it is possible for the central unit to determine both from which patient and from which room an alarm comes. Other technical equipment items connected to network nodes are also uniquely identified.

Staff in the building or buildings have access to or carry handheld units of various kinds which may comprise means making it possible to determine their position. The handheld units are in wireless communication with the network nodes. Communication between patients' alarm transmitters and staffs handheld units can be set up via the central unit so that alarms can be received and responded to by appropriate staff. It is also possible for various types of answering signals to be sent from the handheld units and thereby not only confirm reception of an alarm signal but also send some kind of answer to the patient's alarm transmitter, e.g. that staff are on the way. For this exchange of information, alarm transmitters and handheld units may be provided with simple or more complex indicators and displays. In well- developed versions in accordance with the invention, patients, staff and connected technical appliances exchange qualified information in various forms with the central unit. The central unit may be divided into a number of physi- cal units, both in different buildings and in different establishments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail on the basis of examples of embodiments with reference to the attached drawings, in which Fig. 1 is a schematic general view of an installation in accordance with the invention,

Fig. 2 is a schematic view of part of an installation in accordance with the invention,

Fig. 3 depicts schematically a version of a network node used in Fig. 1 , and

Fig. 4 depicts schematically a version of an appliance with a built-in network node.

THE INVENTION

Fig. 1 depicts an example of an installation executed in accordance with the invention. A physical network links together and makes communication possible between electronic nodes and network units. The physical network takes the form of a conventional electricity distribution network 10, usu- ally with operating voltage 230 V or 115 V a.c, called the power supply network. The installation is confined to an establishment which may comprise two or more buildings. Area limitation is provided by filters or attenuators 36 which may be of a conventional kind.

A plurality of network nodes 11 comprising electrical and electronic components for modulation and demodulation of data signals on the alternating voltage of the power supply network are connected to the electricity distribution network 10. The network nodes make data communication possible between various forms of data equipment, e.g. computers, printers and digital monitoring cameras. In the application depicted in Fig. 1 , a number of mobile units specially adapted to hospital environments, hotel environments and other similar environments are also connected to the network nodes 11. Such adapted units include a monitoring unit 12, an alarm transmitter 13, an handheld unit 14 and an alarm indicator 15. Further units with similar functions may also fall within the scope of the invention. A very simple version of a network node 11 may comprise a remote- controlied electrical circuit-breaker, which is a commercially available and inexpensive product. A free-standing, preferably handheld, unit communicates wirelessly with a mains-connected unit. By means of the free-standing unit it is possible for electrical appliances connected to the mains-connected unit to be activated or, in the particular application, for an alarm signal or the like to be sent via the electricity distribution network.

In the very simplest version, the network node 11 is provided with a push-button for transmitting an alarm signal or the like. The network node may also be provided with a lamp or some other indicator which indicates that the button has been pressed.

The network nodes 11 are controlled and monitored by a central unit 16 connected to the electricity distribution network 10 and having associated ancillary equipment such as an archive or storage unit 17, a keyboard 18 and a monitor 19. The central unit 16 is designed to administer communication between the network nodes 11 and ensure that all the network nodes 11 belonging to the installation are correctly identified by a unique identification code.

The network nodes 11 are preferably provided with means for wireless data communication. Those means may be of a conventional kind and will not be further described here. In more extensive systems in accordance with the invention, the network nodes 11 may be provided with further functions and a greater degree of independence. In the version depicted in Fig. 1 , the central unit 16 is wire-connected to a network node 20 without wireless func- tion, but within the scope of the invention a network node 11 with wireless function may also be used for this purpose. The central unit 16 with associated ancillary equipment and the network node 20 are disposed in a first location 21 demarcated by a broken line in Fig. 1.

Other components are disposed in a second location 22 and a third lo- cation 23. In the example depicted, the third location 23 is divided into a number of rooms equipped with various combinations of network nodes and indicators. The rooms are demarcated by chain-dotted lines. All the locations form part of the establishment covered by the installation in accordance with the invention.

The network nodes 11 may be connected to the electricity distribution network 10 in various ways. In the simplest version, the network node is connected via an ordinary wall socket or lamp socket. With advantage, the network node in such a version is fastened mechanically in the socket to make it difficult to remove and relocate. In environments where there is risk of sabotage, a permanent wired connection to the electricity distribution net- work 10 is used. The wired connection may be in the ceiling or the wall.

Information about the network node's identity and where it is situated is stored in the central unit 16. All communications that take place via the network node can therefore be located with high precision in terms of the building and room from which they originate, including the particular part of the room. The position of units connected via network nodes can thus be located. The network nodes 11 communicate continuously with the control unit. If communication cannot be maintained, an alarm is given. Alarms may be initiated either by the network node or by the central unit 16 or a unit associated with it.

A room 24 is provided with an installation, typical of a hospital environment, in accordance with the invention. A first network node 11 with wireless function is connected to the power supply network 10. A second network node 20 without wireless function connects a control board 25 to the power supply network 10. The control board 25 is connected to various alarm units on or close to a patient in the room 24. A handheld alarm transmitter 13 with various buttons 26 for various alarm levels is accessible to the patient, who can him/herself call for help from staff.

An alarm unit 27 attached to the patient to detect for example his/her pulse and other heart activity gives an alarm automatically upon any form of failure condition. In the version depicted, the alarm transmitter 13 is connected wirelessly to a local network node 11 , whereas the alarm unit 27 is connected wirelessly to the control board 25, which is itself connected to the power supply network via a network node 20 without wireless function. In another version, the respective alarm unit is connected to the power supply network in a suitable manner by wire or wirelessly.

The monitoring unit 12 and the control board 25 are designed for wired or wireless two-way communication and can in one version serve as subcen- tre or slave centre to the central unit 16.

The alarm transmitter 13 and the alarm unit 27 are respectively allocated a specific alarm identity. Other units used in the system in accordance with the invention may be allocated a unique technical identity in a comparable manner. Information about identity accompanies the transmission of alarms and other data so that correct association with the bearer of the alarm transmitter 13 or the alarm unit can be made by the central unit or another comparable unit. The alarm transmitter 13 and the alarm unit 27 may re- spectively be provided with means for measurement of horizontal and vertical position and with an accelerometer to indicate, for example, that the bearer is falling.

An alarm indicator 15 is disposed in or directly adjacent to the room 24. The alarm indicator 15 is also connected wirelessly to a network node 11 and thereby to the power supply network and other units. The alarm indicator 15 may be composite with, or in some other way connected by wire to, the network node 11. An alarm state in the room 24 will activate the alarm indicator 15 so that staff outside the room 24, e.g. in a corridor, are made aware that an alarm has been generated and in which room. The alarm indicator 15 may be activated either by equipment in the room 24, e.g. the control board or a handheld alarm transmitter 13, or via the central unit 16, which is provided with information about the alarm state via the power supply network. The alarm may also be transmitted to personal handheld units 14 or receiver communicators, e.g. in the form of a handheld computer 28, a so-called PDA (Personal Digital Assistant), a pager or a mobile telephone. A well- developed handheld unit or handheld computer can serve as a personal sub- centre in the system. To this end, it will also comprise memory means for storing vital data concerning the patients for whom the bearer of the handheld unit is responsible. By position determination, the handheld unit can guide responsible staff to the appropriate location.

The receiver communicator may also be of a simpler design, e.g. in the form of a minicall unit 29 or a similar unit. In an advantageous version, the receiver communicator is provided with a display for reading alarms and other information, and with function buttons for confirming receipt of information and being able to send at least simple messages to the central unit 16 and other units.

The central unit 16 is important for the functioning of the system in accordance with the invention. The central unit stores information about staff, techniques and desired patient-specific information concerning medical condition, status and medicines. Each patient admitted is associated with a spe- cific alarm unit 26 and/or a specific alarm transmitter 13, whereby alarm signals transmitted to the central unit 16 via a network node 11 and the electricity distribution network are automatically related to the correct patient. Alarms and other communications from and to the patient pass via a network node 11 whereby the current geographical location of the alarm unit or some other communicating unit is known.

Within the scope of the invention, the central unit 16 may be divided into a number of separate computer units. The computer units may be disposed in different spaces and different buildings. Communication between the computer units may be via the electricity distribution network in the same manner as described above for other technical equipment items, but also via conventional communication channels, e.g. wired data networks and wireless data communication. With advantage, conventional communication technology is used if the computer units are disposed in different establishments with separate electricity distribution networks.

The storage unit 17 connected to the central unit 16 stores the data required for handling in real time various applications within the scope of the invention. Settings, messages and other activities are saved to cater for traceability. With advantage, the storage unit 17 comprises movable storage media for security copying and long-time storage. Information may also be moved or copied to patients' other records after their care has ended.

Wireless communication between the network nodes 11 and handheld alarm units and other mobile units takes place on an available carrier frequency, e.g. 868 MHz, using with advantage available protocols and communication systems. To enhance security against mutual overhearing between different floors of a building, two or more carrier frequencies may be used simultaneously. It thus also becomes possible to determine continuously the current position of alarm transmitters 13, alarm units 26 attached to patients, handheld units 14 and other wirelessly connected units. A comparable division into two or more carrier frequencies may also be done in order to separate different groups on the same floor of a building.

The system in accordance with the invention affords a number of possibilities for locating the position of units. In addition to the possibilities described above, mobile units may be provided with special means for locating their position, e.g. by giro. A giro position-determining means may continuously emit signals which indicate the position of the mobile unit. The meas- urement principle is based on inertia navigation with measurement of the movement of an object. Position location by giro may with advantage be used in configurations with widely spaced network nodes.

Position location may also be facilitated by limiting the transmitter power of mobile units and hence their range. The transmitter power may be set so that communication between mobile units and network nodes is limited to a settable distance, e.g. within a room or floor of a building.

Simple mobile units, e.g. alarm transmitters 13, handheld units 14 and minicall units 29, usually transmit only a few types of signals to one or possibly a few receivers, and also communicate information about their own posi- tion or the like. Alarm transmitters 13 may be provided with indicators, e.g. lamps or LEDs, to provide the user with information that an alarm has been received or that staff called are on the way. In some applications, the alarm transmitters 13 and other mobile units are provided with a display to make it possible to convey more complex information, e.g. instructions about medication or route directions for taking a patient to a desired location. The hand- held units 14 and minicall units 29 intended for different staff categories may also be provided with a display and a set of buttons to enable various forms of communication.

The communication facility provided by using the electricity distribution network as a communication medium can also be used for more conventional conveying of information. This is illustrated in Fig. 1 by a conventional computer 34 and intercom telephones 35. The computer 34 and the intercom telephones 35 are provided with either built-in or external network nodes and communicate with other comparable units via the network nodes and the electricity distribution network. The computer 34 and the intercom tele- phones 35 may be designed for both wireless and wired communication via the network nodes.

An installation designed in accordance with the invention may also comprise devices for accumulating information and/or controlling commonly used mechanical equipment. In Fig. 1 , this is illustrated by an electric motor 37 connected to the central unit 16 via a network node 20 without wireless function. The electric motor 37 may form part of a hoist, a fan or some form of ventilation equipment.

The portion depicted in Fig. 2 of an installation in accordance with the invention comprises an alarm indicator 15 and a route indicator 30 fitted in a corridor ceiling. When an alarm is activated by a network node 11 in a room, the control unit can, through knowing where the network node 11 and staff are, indicate the way to the room and the network node. This may be done by the activation of indicators, e.g. lamps, LEDs or graphic displays 31 , on route indicators 30 along an appropriate route for certain staff. An alarm in- dicator 15 adjacent to the room in which the alarm has been activated will also light up, as depicted in Fig. 2. The version of a network node 11 depicted in Fig. 3 is intended for insertion in a conventional wall socket like an ordinary plug. Wall sockets and plugs occur in different versions in different countries and the network nodes 11 are adapted to the particular situation. Two pins 32 protruding from a rear side of the network node fit into corresponding apertures in the wall socket.

In the version depicted, the network node 11 is intended to be fastened in a wall socket screwed permanently to a wall. This is catered for by the network node being provided with holes 33 running through it in a configuration corresponding to that of the wall socket's fastening screws (not de- picted). This version makes it possible to fasten the network node 11 in and to the wall socket. In the version depicted, the network node also comprises an antenna 34. The antenna 34 is dimensioned for the frequency range used in wireless communication between network nodes and mobile units. In some versions the antenna is built in.

Network nodes directly and permanently connected to the electricity distribution network are designed as appropriate for this type of connection. It is also possible for electrical appliances used in buildings covered by an installation in accordance with the invention to be provided with a built-in network node. Upon connection of such an appliance to the electricity distri- bution network, the network node automatically becomes available for communication with other network nodes and the central unit.

An example of a network node 38 built into an appliance 39 is illustrated in Fig. 4. The appliance 39 may be a dialyser, a respirator, a supervisory monitor or some similar device, with or without medical function. The network node 38 comprises a mains module 40 corresponding technically to a network node as described above with electronics for transmission of data signals on electricity distribution networks. The mains module 40 in Fig. 4 is connected to the distribution network 10. This connection also provides the appliance 39 with power supply.

The built-in network node 38 also comprises a data capture module 41 and a control module 42 which are connected to an electronic module 43 be- longing to the appliance 39. The data capture module 41 is fed with and stores information concerning patients, care staff who handle the appliance and technical care concerning the treatment in which the appliance is used, alarm limits and current operating data of the appliance. The operating data stored may include chemical levels, battery voltage, operating times, temperatures and similar data.

In this context, important data concern any possible leakage currents in protective earth lines and any possible electrical connection with the patient. When leakage currents of a certain strength occur, an alarm signal may be emitted to the central unit 16, or some other comparable unit, via the built-in network node 38. Many appliances used in medical care, e.g. respirators and dialysers, cannot switch off automatically when leakage currents occur, since this might put the patient's life at risk.

The control module 42 handles certain functions of the appliance, e.g. log-in of operating staff, approval of connection to patient, medical remote control for stopping ongoing treatment and approving treatment by defibrillator and similar special equipment. The control module 42 is also designed to cater for various appliance settings required for treatment by the appliance and for altering technical settings and calibrating units in the appliance. Other functions of the control unit 42 are within the area of communication, e.g. for showing the current status of the appliance and other information and recording control commands and transmitting them to the electronic module 43.

The electronic module 43 comprises substantially functions of conven- tional kinds for the control and monitoring of appliances. Communication with external control and monitoring equipment, e.g. a central unit 16, is via the mains module 40. The user and/or staff can use an input and output unit 44, which may for example comprise a display and a set of buttons, for controlling and monitoring the appliance in a more conventional manner. Com- munication via the electricity distribution network takes place at a number of levels. The primary information carrier is any of the PLC, ADSL or other comparable technologies available on the market. These techniques carry an alarm and control protocol adapted to the invention for exchange of information between the various functions in the system. The protocol is a dynamic protocol which adapts the amount of information to what is the most optimum at the time. This means that each actual amount of information is preceded by opening information and ended by closing information. This takes place at various levels and applies to each individual information module and out to cover the whole protocol.

The protocol is composed of various information modules. There are modules for activity, identity, info code, security code, routine, patient information, staff information, technical information, data and spare modules to cater for future needs. For a very time-critical and acute alarm, the protocol comprises few but vital amounts of information about activity (type of alarm) and identity concerning the patient, equipment item, time and geography to which the alarm refers and its own unique info key. The central unit has to use the minimised amount of information to decide about receiving the alarm and its further handling.

When both time criteria and data volumes are relatively high, the information module is provided with data with an info key enabling direct con- trol of information from transmitter to receiver. This may for example apply to transmission of speech for intercom telephony, ECG or some other current amount of information. When time criteria are low and no other protocol needs space in the network, the protocol may be made long and complete with all the information modules and large volumes of information.

There follows a brief description of the various information modules.

Activity indicates the type of alarm to which the protocol refers, e.g. acute alarm, service alarm, attention alarm etc. and variants of the alarm types heart, toilet visit, imminent end of paper and so on.

Identity denotes transmitter, selected receiver, geographical location, point in time, technical ID and the like. Info key creates an identity for the amount of data and the information process created.

Safety key locks and encrypts the protocol. The safety key also serves as a certificate for obtaining permission for the protocol to pass fire- walls and enter the various system units, and permission to amend stored information. The subtlety of the safety key is that all executable codes must have an approved key to obtain time in a processor which is to execute the code. This security concept permeates all the system components that use computer programmes for their function, and covers both technical units and, where necessary, particular or all protocols.

Routine indicates how information is to be handled and what is expected from the recipient.

Patient information is concentrated vital information about the patient.

Staff information is concentrated vital information about staff.

Technical information is concentrated vital information about technical matters and information content.

Data is the actual amount of data in cases where it is too large to fall within the above.

Development is a space which may be required to meet future needs.

Claims

1. A method for communication via an electricity distribution network (10) in an establishment, whereby data signals are transmitted via network nodes connected to the electricity distribution network, c h a ra c t e r i s e d

in that information about the physical location of the network nodes (11 ) and a unique identity for each network node (11 ) are stored in a storage unit (17) of a central unit (16),

that the network nodes (11 ) are wirelessly connected to mobile units (13; 14; 15; 27; 28; 29),

that communication between mobile units (13; 14; 15; 27; 28; 29) takes place via network nodes (11) and the electricity distribution network (10) and

that information communicated between mobile units (13; 14; 15; 27; 28; 29) is recorded and stored in the central unit (16).

2. A method in accordance with claim 1 , whereby the positions of mobile units (13; 14; 15; 27; 28; 29) are determined on the basis of the prestored physical location of the network node through which the particular mobile unit communicates.

3. A method in accordance with claim 1 , whereby network nodes (11 ) are grouped by allocation of different carrier wave frequencies or other compara- ble channel allocation.

4. A method in accordance with claim 1 , whereby the transmitter power of mobile units (13; 14; 15; 27; 28; 29) is limited so that communication between mobile units and network nodes is confined to a settable distance.

5. A method in accordance with claim 1 , whereby data signals transmitted in the electricity distribution network are attenuated at boundaries of the establishment.

6. A method in accordance with claim 1 , whereby signals indicating the position of mobile units (13; 14; 15; 27; 28; 29) are continuously emitted to the central unit (16).

7. A device for communication via an electricity distribution network (10), whereby a number of network nodes (11 ; 20) are connected to the electricity distribution network (10), c h a ra c t e ri s e d

in that the network nodes (11 ; 20) are connected to a central unit (16),

that the central unit is designed to communicate necessary addressing information to the network nodes,

that network nodes (11 ) are wirelessly connected to mobile units (13;

14; 15; 27; 28; 29),

that the central unit comprises a storage unit for recording and storing such communication information exchanged between the network nodes.

8. A device in accordance with claim 7, whereby an alarm unit (27) attached to a patient is wirelessly connected to a network node (11 ).

9. A device in accordance with claim 7, whereby a plurality of alarm indicators (15) are connected to the central unit (16) via the electricity distribution network (10).

10. A device in accordance with claim 7, whereby a network node (20) without wireless function is operatively connected to an electrical machine (37).

11. A device in accordance with claim 7, whereby network nodes (11 ; 20) are mechanically connected to electrical wall sockets.

12. A device in accordance with claim 7, whereby mobile units (13; 14; 15; 27; 28; 29) are each provided with an indicator and a display.

13. A device in accordance with claim 7, whereby alarm transmitters (13) are each provided with an indicator to confirm that an alarm has been sent and received.

14. A device in accordance with claim 7, whereby a plurality of route indica- tors (30) are connected to the central unit (16) via the electricity distribution network (10) so that a route for staff to reach an alarm location can be indicated by activation of route indicators (30) along the way.

15. A device in accordance with claim 7, whereby mobile units (13; 14; 15; 27; 28; 29) are each provided with a giro unit for their continuous position location.

16. A device in accordance with claim 7, whereby handheld units (14; 28; 29) associated with staff are provided with memory means with patient data.

17. A device for connection to and communication via an electricity distribution network (10), whereby at least one appliance (39) is connected to the electricity distribution network (10), c h a ra c t e ri s e d

in that the appliance (39) comprises a network node (38) built into it and connected to the electricity distribution network (10),

that the built-in network node (38) is connected to a central unit (16),

that the appliance (39) comprises measuring means for measuring the functional state of the appliance (39),

that the appliance (39) comprises a mains module (40) for transmitting functional state data to the central unit (16),

that the central unit comprises a storage unit for recording and storing such communication information exchanged between the network node and the central unit (16).

18. A method for transmitting information via an electricity distribution network (10), c h a r a c t e ri s e d the information is divided into a plurality of modules whereby different modules comprise at least information about activity, identity, security key, patient, technical apparatus and data.