EP1244083A1 - Method for collecting consumption data - Google Patents

Abstract

A radio base station (1) uses relay radio modules (20,21,22) to maintain a direct or indirect connection with all the radio modules for a data-collection system. Each radio module is allocated a point in time in which it transmits data for purposes such as energy consumption. After transmitting such data, each radio module receives confirmation with a synchronization command.

Description

The present invention relates to a method for Acquisition of data, especially measurement data such as Consumption data, according to the preamble of claim 1. A such a method is known from DE-A-199 11 657. A There is often a major problem with data collection in that the individual radio modules for transmitting the collected data to the base station acting as a collection point are battery operated and therefore with the available Energy needs to be handled very economically. The wireless data transmission is just in the Building services, e.g. when recording heat consumption, then of particular interest if existing installations are moved or need to be retrofitted by any wiring eliminated.

The aim of the invention is the transmission and reception times and thus the energy requirement and the occupancy of the available To keep the frequency band as low as possible. That goal will achieved according to the characterizing part of claim 1. The Sending and receiving times of the individual radio modules can be kept very short by the short time one for sending the collected data immediately short reception follows during which the Confirmation of receipt is given, which if necessary only can consist of a synchronization command. With that is in short time and with correspondingly low energy consumption clarified that the job is done and that Radio module until the next data transmission due date does not have to be ready to send or receive. advantageous Refinements of the method according to the invention result from the following description, the drawings and the Claims.

Fig. 1

die grundlegende Organisation eines Datensammelsystems,

Fig. 2

ein praktisches Beispiel eines derartigen Systems, und die

Fig. 3 und 4

Diagramme zur Erläuterung von Bedingungen zur Sicherstellung der Datenübertragung.

The drawings show:

Fig. 1

the basic organization of a data collection system,

Fig. 2

a practical example of such a system, and the

3 and 4

Diagrams to explain conditions to ensure data transmission.

1 shows the base station 1, also called ComServer in the following, which is directly or indirectly connected to a number of radio modules 2 by radio. All radio modules are preferably constructed identically, ie they have a transmitter and a receiver, memory for storing collected data and also either a measuring device for recording data or a connection via a suitable interface with a measuring device, for example an existing one, installed meter. As shown in FIG. 1, the radio modules are hierarchically arranged in those that have a direct connection to the base station 1 and are assigned to a level 0 (2 ₀ ), radio modules 2 _{1 to} a level 1, which have one or more radio modules of level 1 are connected and radio modules 2 _{2 of} a stage 2. This is to indicate that the base station 1 has only a connection with some of the radio modules assigned to it or subordinate to it, and that the relay function of intermediate modules 2 ₀ and 2 ₁ required.

1 clearly shows the hierarchical structure of the system, but not an optimal structure, because in levels 0 and 1 each carries a single radio module the load of Relay function for all subordinate radio modules. In Fig. 2 indicates that communication between the individual radio modules and the base station over several Paths can be made, a distinction being made between in bold lines denote primary communication paths and secondary or denoted in thin lines alternative communication paths. It means that one each during commissioning Communication path is determined, via which in operation the data are transmitted. Will this be primary Communication path interrupted during operation to Example because a tenant changes the furniture changes the system automatically switches to an alternative Communication path. The alternative communication paths are searched for when installing the system and bookmarked. The system can also be used at any time Look for alternative communication paths, as explained earlier becomes.

The system is largely commissioned automatically. Each radio module 2 is installed before ComServer 1 logged on. Every radio module receives automatically an identification address and one Initial send time assigned by the ComServer. Either Identification address and initial send time come in entire system only once. After logging in on ComServer the radio module is in initialization mode. In this mode the module transmits every time A message with when his initial sending time is reached his identification address. The fully automatic Commissioning is now described in more detail.

1st commissioning step (all modules are level 0 certainly)

Each module that is in the initial state sends its identification (address that was assigned when logging on to the ComServer) at its initial send time. If the server has received the module's telegram, it gives it the subaddress 0 and a time of transmission. The radio module now changes to the operating state. In the operating state, the radio module contacts the ComServer each time the transmission time is reached.
Remarks: The server knows all modules of level 0 after one day. This procedure can already be carried out during the installation.

2nd commissioning step (all modules are level 1 certainly)

The server addresses the level 0 modules and indicates the initial send times of missing radio modules. At these times, the modules of level 0 should listen. Then a day passes. Each level 0 module listens at the specified times and registers each module from which the identification can be received.
Each level ₀ module tells the ComServer from which other modules the identification could be received; this takes place the next time the transmission time is reached. The ComServer now determines the communication paths and instructs the level 0 modules, which are to be used as a relay station, to put the level 1 modules into operation.
The ComServer instructs the level 0 modules to put the level 1 modules into operation:
The level 0 module waits for the initial end of the level 1 module to be put into operation. This reports at the time of initialization. The module of level 0 answers and announces the new subaddress and the reception time window for the module of level 1. If the module of level 0 has received the receipt of the level 1 module, this can be communicated to the ComServer the next day.
Comment:
The server knows all level 1 modules after two days.

3rd commissioning step (all modules are level 2 certainly)

The ComServer must ask the level 1 modules whether they can receive a telegram at the initial send time of a missing module. For this purpose, inquiries are sent to the level 1 modules. The command is passed from level 0 modules to level 1 modules. These listen to a telegram in the specified time window. One day is needed for this. Two days pass before the results return to the ComServer. Another day is required to provide the level 2 modules with a subaddress and reception time window. Confirmation of successful commissioning is due after a further 2 days.
Note: The server knows all level 2 modules after six days.

Commissioning time

The times for the commissioning described above Levels are valid if for every module within 24 Hours only one broadcast time is assigned. The Commissioning a radio system can take up to 9 days take. However, this procedure can be accelerated by for the commissioning of each module several transmission times be allocated. However, care must be taken that the duty cycle of each module is not is greater than 0.1%.

The radio system can be supplemented with additional modules at any time become. To do this, the modules only have to be registered on the ComServer commissioning takes place exactly the same as this is described in the paragraph "Fully automatic commissioning" is.

Removing radio modules

To remove a module, all you have to do is log it off on the ComServer. This can be done by entering the keyboard on the ComServer. The deregistration can also be carried out "automatically" by inserting the module to be deregistered into the chip card interface of the ComServer and entering "Deregister" on the ComServer.
If the deregistered module is a module used as a relay station, certain modules of the subsequent stage (s) lose contact with the ComServer. These modules automatically change to the initial state and can therefore be put into operation again. The procedure is identical to the first commissioning of the modules.

Replace the ComServer

The network structure, the reception time windows and the initial transmission times of the individual modules are stored in the ComServer. So that a connection to the radio modules can be established when the ComServer is replaced, at least the initial transmission times of the modules must be saved on a non-volatile storage medium.
If the ComServer is replaced, the storage medium is removed from the old ComServer and used in the new one.
The radio module of the old ComServer must also be used in the new one, otherwise the synchronization between the ComServer and the level 0 modules will be lost. If the radio module of the ComServer also has to be replaced, the synchronization with the modules of level 0 is also lost. In this case, the ComServer must be ready to receive until it receives the message from a module. Thanks to the data stored in the storage medium, the timer of the ComServer can then be synchronized.

Synchronization of the radio modules Synchronization of level 0 modules during commissioning and in operation:

After a module has sent a telegram, it switches ready to receive a response from the Receive ComServers. Since the ComServer the time of transmission knows each radio module, it can determine the deviation, with which the module sent the telegram. This Deviation will be the level 0 module as part of the answer sent back. The level 0 module can now use its timer correct according to the deviation.

Synchronization of level 1 and level 2 modules at the Commissioning and in operation:

The synchronization of a level 1 or level 2 module is the same as a level 0 module, except that instead of the ComServer a relay station (level 0 resp. Level 1 module) occurs.

Reading the meter data

The meter data is read out via the interface according to ISO 7816 (smart card). The data is stored in the radio module cached and at agreed times, e.g. transmitted to the ComServer once a week. The data are read out regularly at defined times. It but there is also the possibility that by a command an additional reading is triggered on the ComServer.

There now follow further details and considerations of how it works of the system.

Quartz frequency tolerances

The frequency of the quartz can be measured precisely during production (final test). A deviation from the target frequency can now be approximately compensated during operation, since the actual frequency is known.
The relationship between frequency and temperature follows the quadratic function: Δƒ / ƒ = -k · (DD 0 ) 2 [Ppm] where for T ₀ the temperature is used at which the vertex of the function is located.
Because of the quadratic course of the function, the frequency always decreases when the temperature deviates from T ₀ .
In the event of a deviation of 50 degrees from T ₀ , for example: at approximately 75 degrees, a frequency deviation of 95ppm can be expected. This 95ppm deviation causes a deviation of a module timer of 8.21s / day, if you still take into account the variation within the series (about 10%) even about 9.0s / day.

Assuming that about 85% of the temperature-related Drifts can be compensated by a temperature measurement the maximum deviation of a module timer is reduced to about 1.35s / day.

Receive window and send cycles

The current consumption of the Receiver relatively large. To be as long as possible To be able to realize the battery life would have to be the reception readiness should be set as short as possible. So that the inaccuracies due to the temperature-related Drifts of the quartz frequency can be reliably absorbed the receiver must be open for as long as possible So there has to be a compromise between energy needs and Compensation ability can be found.

Nutzbare Kapazität der Batterie

Drift und Toleranz des Quarzes, resp. Genauigkeit der Temperaturkompensation.

Vorschrift bezüglich Dutycycle und "Sendepausen"

Anzahl der Module in einem System

Dauer die ein Modul im "Funkschatten" sein können muss, ohne "endgültig den Kontakt zu verlieren"

In addition to the available battery capacity and drift of the quartz frequency, there are a few other points to consider when determining the reception window. Overall, the following factors influence the duration of the readiness to receive:

Usable capacity of the battery

Drift and tolerance of the quartz, resp. Accuracy of temperature compensation.

Regulation regarding duty cycle and "transmission breaks"

Number of modules in a system

Duration that a module must be able to be in "radio shadow" without "finally losing contact"

Because of the dependence of the quartz frequency on the temperature, the following two situations can occur:
The quartz temperature of the transmitter module deviates more from the calibration temperature than that of the receiver module. The frequency of the quartz is therefore lower, the timer of the transmitter lags behind the timer of the receiver.
The quartz temperature of the transmitter module deviates less from the calibration temperature than that of the receiver module. The transmitter's timer precedes the receiver's timer.

If you consider the two situations in the graphic Fig. 3 represents together, the requirements for sender and Receiver clearly visible:

• t_TI < t_RR
• t_TS > (Δt_CIk - t_RR/2)
• t_TE - t₀ > (Δt_CIk - t_RR/2)

The following conditions must be fulfilled for reliable communication:

• t _TI <t _RR
• t _TS > (Δt _CIk - t _RR / 2)
• t _TE - t ₀ > (Δt _CIk - t _RR / 2)

The duration of the reception window must not be shorter than that prescribed transmission pause can be selected. In order to it is ensured that at least one attempt Establish connection within a reception window takes place, the interval of the connection establishment be shorter than the reception window. To determine the minimum duration of the reception window, the time must still are added, which is required for communication. Assuming that for the telegram (including switching on of the transmitter) 30ms are required, the Willingness to receive last at least 750ms. If another Small reserve should be provided, the duration of the Willingness to receive is about 800 to 900ms long. Accordingly, the interval of connection establishment between approx. 760 and 860ms long. Now become the well-known Values used in the graphic Fig. 3, the 4 derive:

From Fig. 4 it can be seen that a synchronized In the worst case, radio module has to try 4 times Make connection, with each attempt the whole Telegram is sent. This leaves 3.48s in this case within the opened hour for data transmission left.

If a module cannot establish a connection for any reason, it cannot be synchronized. So that the connection can be established in the next allocated time range, the number of attempts to establish a connection must be increased. The number of these attempts is therefore a function of the time that has elapsed since the last successful synchronization. The number of attempts is increased by 4 for each day on which synchronization was not possible. The attempts to establish a connection are distributed symmetrically in time around the time T ₀ .

The time window in which a connection is established can, grows by 4 times 760ms every day, i.e. by 3.04s. this time window (from the second day) increases by approx 10% stronger than this for the assumed values for the Deviation of the quartz frequency would actually be necessary.

Connection establishment and synchronization

The connection is always established by a "UpStream telegram". Communication is always from initiated at a subordinate level. Would Communication started with a "DownStream telegram", the number of modules of the lower level would have to be due to the Restriction of the duty cycle can be severely restricted. In addition, during commissioning and operation, the same procedures are used. After the module of higher level has received the telegram, answers it with an instruction to the module that communicates initiated. The answer includes next to the Command (s) also the synchronization data to align the Module timer. Thus, the timer of a radio module is on the Timer of the module of the higher level synchronized. Since this transmission time of this answer is very short, a radio module has a very large number of subordinate ones "Operate" modules. This is especially true for the ComServer significant.

system limits

Taking into account the previous chapter, the maximum system size can be determined.

Maximum number of modules in the system

Each module is assigned its own time range in which it contacts the higher-level module. The duration this time period is chosen so that there are two Do not overlap time periods even if an or multiple modules on multiple consecutive days are not can be synchronized:

With a telegram transmission duration of 30ms, according to Regulation of one module within one hour 120 telegrams are sent, with between two Telegrams are 760ms. This results in a time range of 91.2s assigned to each module. Overall, can 947 different time ranges within 24 hours be placed. The time range is only after 30 days without Synchronization fully used. Since the time ranges at modules that are not synchronized must "move" between the Time ranges of two radio modules each are not used time range. That way ensures that all modules within the system on 30th Reconnect the day after the last synchronization can manufacture. A radio system can therefore consist of one ComServer and up to 474 radio modules exist. The Time ranges of two modules may also overlap. In this way, more radio modules could be combined in one system. Because of the low occupancy of the frequency band of maximum 0.1% per module, the probability is relatively low, that two modules send at exactly the same time. With the above The limitations described can reduce this risk entirely be excluded.

Maximum number of modules of level 0

The level 0 modules are in direct contact with the ComServer. Since the duty cycle is also restricted for the ComServer applies, the number of level 0 modules is determined by the length of the DownStream telegrams from the ComServer to the level 0 modules certainly. The ComServer has 474 level 0 modules 182ms available for each DownStream telegram. In These 182ms can both synchronization signals as well Commands are transmitted. Because in the direction of the ComServer no consumption data are transmitted to the radio modules, broadcast time is no longer required. This should be for this Function should be sufficient.

Maximum number of modules of levels 1 and 2

Since the data that has to be passed from a module of level 1 or 2 via at least one relay station, it can take up to two days before the data arrives at the ComServer. Therefore, a radio module should only be assigned to level 1 or 2 if it is outside the range of the ComServer.
The modules of levels 1 and 2 use different radio modules as relay stations. Since the storage capacity and computing power of the radio modules is limited, the number of "sub-modules" that a single radio module can have must be limited.

Offer one level 1 or 2 radio module several Communication paths to the ComServer are the primary Select communication paths so that each relay station receives as few sub-modules as possible.

Energy requirements of the individual modules Consumption for communication in the initial state

In the initial state, the radio module sends out its identification address each time the initial transmission time is reached. The telegram with the identification address including CRC, interleaving etc. is 16 bytes long. At a transmission rate of 4800 bit / s and 8 bits per byte (synchronous data transmission), the identification address takes 26.7ms to be sent. To ensure that the telegram also reaches a receiver, the radio module must establish the connection as described above. Every day on which no connection can be established, the initial send time and the receive window of potential communication partners can drift apart. The time window in which communication can take place increases every day according to the chapter "Tolerances of the quartz frequency"
1.35 s for a total of 2.7s. So that the radio module can be registered even after several days, it must increase the number of telegrams sent every day.

energy balance

• Je Funkmodul gibt es nur einen Initialsendezeitpunkt innerhalb 24 Stunden.
• Am ersten Tag des Initialzustandes werden 4 Telegramme ausgesendet.
• An jedem weiteren Tag des Initialzustandes werden 4 zusätzliche Telegramme ausgesendet.
• Nach dem Senden der Identifikationsadresse wird der Empfänger für einige ms eingeschaltet.
• Bei erfolgreicher Anmeldung wird ein Telegramm von dem übergeordneten Modul empfangen.

Assumptions for determining energy consumption:

• There is only one initial transmission time per radio module within 24 hours.
• 4 telegrams are sent on the first day of the initial state.
• On each additional day of the initial state, 4 additional telegrams are sent.
• After sending the identification address, the receiver is switched on for a few ms.
• If the registration is successful, a telegram is received by the higher-level module.

Each module may not transmit its transmitter for longer than 3.6 s turn on within an hour. If the Frequency band during 30 ms per UpSream telegram may be in a maximum of 120 telegrams can be sent per hour. This enough for one radio module for 30 days in the initial state to be able to operate. The 120 telegrams are in Intervals of at least 720 ms sent. All Telegrams can therefore be sent from a radio module within it allocated time range. Should be more than 30 days in the initial state can be bridged (e.g. because a relay station has failed and none offers alternative communication path), the module additional reception windows at the higher level allocated or the reception window extended so that the module in the initial state the time between two Transmissions of the telegram can extend. But it has to care is taken that the allotted Do not overlap time periods of two modules.

Consumption for communication in the operating state (worst case)

It should also be clarified that FIG. 2 only shows the example shows the available connection options. In concrete terms As mentioned, there are predefined paths via which traps data transmission is running as long as there is no fault. Only then will the base station become active and look for one Substitute path, according to the ones described above Steps. Fig. 2 also does not show that one can Possibility of designing the network so that the Relay station serving radio modules about the same number of via modules communicating with them, so all modules have similar loads and are therefore roughly the same Have operating time without changing the battery.

The radio network can also be expanded in the sense that the base station via radio with a parent Data processing center is connected. It can do that local radio network shown here and described above 1, 2 that for example for recording the heating energy or - A similar, more powerful radio network serves costs be parent, which is also an existing one Modbilfunknetz can act.

Claims (11)

Method for acquiring data, in particular consumption data, data being transmitted from at least one radio module (2) to a radio base station (1) directly or indirectly via a radio module (20, 21) serving as a relay, characterized in that each radio module ( 2) a certain point in time for the transmission of data is allocated, and that each radio module is switched to reception immediately after the transmission of the data in order to receive a confirmation with a synchronization command. A method according to claim 1, characterized in that the gear deviation of the clock of a radio module is determined and a gear correction command is transmitted. A method according to claim 1 or 2, characterized in that the synchronization between base station (1) and thus directly communicating radio modules (20) and between relay radio modules (20, 21) and communicating radio modules (21, 22) follows. Method according to one of claims 1-3, characterized in that the speed of the clocks of the radio modules is corrected as a function of their temperature. Method according to one of claims 1-4, characterized in that the radio modules are assigned reception time windows which are symmetrical to the transmission times of communicating radio modules. Method according to one of claims 1-5, characterized in that initially certain transmission paths are defined, for which a replacement path is determined only in the event of a fault. Method according to claim 6, characterized in that both during the initial start-up and in the event of a fault, the transmission path (s) is or are determined and determined by an automatic initialization program of the base station (1). A method according to claim 6 or 7, characterized in that all existing relay radio modules (20, 21) are assigned as equal as possible a number of subordinate radio modules (21, 22). Method according to one of claims 6-8, characterized in that relay radio stations (20, 21) radio stations with the lowest rate deviation of the clocks are subordinate. Method according to one of claims 1-9, characterized in that data is transmitted by radio from the base station to a higher-level data processing point. Application of the method according to claim 1, for detection heat consumption, especially for calculating heating costs, a radio module is assigned to each radiator.

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