DE10353337A1 - Time division multiple access system operating method, involves transmitting cyclic data transfer blocks via wireless nodes, and assigning minimum of two time slots to one wireless node - Google Patents

Abstract

The method involves transmitting cyclic time division multiple access (TDMA)-data transfer blocks via multiple wireless nodes (S.1, S.2, S.3, S.4, S.k, S.k+1, S.k+2, S.k+3, S.k+4, S.I). Each data transfer block is assigned with successive time slots. One of the nodes is assigned with minimum of two time slots, which are joined together. A reception-actuation signal is generated between the two joined time slots.

Description

The The invention relates to a method of operating a system multi-node and one base station according to TDMA according to the preamble of the claim 1.

The For example, the invention may be implemented in a system having a plurality wireless sensors and / or actuators (nodes) and a base station used which is used in a machine or plant, for example industrial robots, Manufacturing machine or production machine is installed. When Sensors or actuators can Proximity switches / proximity sensors, Temperature measuring sensors, pressure measuring sensors, current measuring sensors or voltage measuring sensors or micromechanical, piezoelectric, electrochemical, magnetostrictive, electrostatic or electromagnetic actuators are used.

• – jeder Näherungssensor mindestens eine zur Energieaufnahme aus einem mittelfrequenten Magnetfeld geeignete Sekundärwicklung aufweist,
• – wobei mindestens eine von einem mittelfrequenten Oszillator gespeiste Primärwicklung zur drahtlosen Versorgung der Näherungssensoren mit elektrischer Energie vorgesehen ist,
• – und wobei jeder Näherungssensor mit einer Sendeeinrichtung ausgestattet ist, welche interessierende Sensor-Informationen beinhaltende Funksignale an eine zentrale, mit einem Prozessrechner der Maschine verbundene Basisstation abgibt.

In the DE 199 26 799 A1 a system for a plurality of wireless proximity sensors having machine, in particular production machine, proposed

• Each proximity sensor has at least one secondary winding suitable for absorbing energy from a medium-frequency magnetic field,
• Wherein at least one of a medium-frequency oscillator-powered primary winding for wireless supply of the proximity sensors is provided with electrical energy,
• - And wherein each proximity sensor is equipped with a transmitting device which outputs sensor information containing interest radio signals to a central, connected to a process computer of the machine base station.

at this wireless system is eliminated compared to conventional solutions with wire / cable connection for electrical power supply and communication through Planning, material, installation, documentation and maintenance related relative high cost of wire / cable connections. There can not be any failures of cable breaks or bad, such as corroded contacts occur.

In the DE 199 26 562 A1 For example, there is proposed a method and arrangement for wirelessly supplying a plurality of actuators with electrical energy, an actuator and a primary winding therefor, and a system for a multi-actuator machine, wherein the proposed technology for power supply and communication is similar to that described above for the DE 199 26 799 A1 specified technology is.

For the radio transmission is preferably the TDMA technology (Time Division Multiple Access) used, in which the information from / to the actuators or sensors (Node) is transmitted in the form of cyclic TDMA frames, wherein each sensor / actuator has a specific time slot within a Assigned to the data block is.

From the DE 101 16 285 A1 For example, a method of operating a multi-node system and TDMA (Time Division Multiple Access) base station is known wherein TDMA burst frames are transmitted and each TDMA frame is composed of successive successive time slots, each time slot associated with a particular node is. At the beginning of each time slot of the previous TDMA data transmission block set for this time slot gain value is taken in the receiver of the base station as a default value and preset.

From the DE 101 16 286 A1 For example, a method of operating a multi-node system and a base station according to TDMA is known, wherein TDMA cyclic frames are transmitted and each TDMA frame is composed of successive successive time slots, each time slot being associated with a particular node. At the beginning of each time slot, the frequency deviation-related DC component or the phase rotation in the receiver of the base station set in the previous TDMA frame for this signal detection time slot is adopted and preset as the default value.

at Establishment of the Protocol - more precisely Communication Protocol - (Agreement on Behavior and formats in communication among remote partners, d. H. a protocol determines how communication between a transmitter and a receiver perform is for the mentioned above wireless systems, it is necessary to input and outputs one certain data length assign, for example, 8 bits for inputs and 8 bits for outputs. For newer (later) Applications, it is quite possible that, due in the meantime increased Requirements for individual nodes have a larger data length - for example 32 bit - required or at least desirable is.

The invention has for its object to provide a method for operating a system with multiple nodes and a base station according to TDMA of the type mentioned, which he advanced input / output capability of individual nodes allows.

These The object is achieved in conjunction with the features of the preamble according to the invention solved specified in the characterizing part of claim 1 features.

The particular advantages of the invention are that the extended input / output capacity of individual nodes without change underlying structures of once (at an earlier date) established communication protocol is realized. All in all can be a larger amount of data wirelessly transmitted in the system become. It's an individual and flexible fit for everyone Node required data length possible. earlier Nodes with reduced data length (for example, 8 bits) in the same system together with new nodes with increased data length (for example 32 bits) coexist. The management functions of the system can be essentially unchanged be maintained. Although additional functions require new commands, however, the original remains Structure of the protocol intact.

Further Advantages will be apparent from the following description.

advantageous Embodiments of the invention are characterized in the subclaims.

The Invention will be described below with reference to the drawing Embodiments explained. It demonstrate:

1 a system having a plurality of nodes communicating wirelessly with a base station,

2 a cyclic TDMA frame,

3 a sequence of successive successive frames,

4 a time slot of a TDMA frame.

In 1 is a system with a plurality of wirelessly communicating with a base station nodes, preferably sensors and / or actuators shown. There are a plurality of nodes S.1, S.2, S.3, S.4 ..... Sk, S.k + 1, S.k + 2, S.k + 3, S.k + 4 ..... SI provided, which are installed, for example, within a plant or attached to a machine, in particular a production machine, wherein
k = run index of a given node and
I = (total) number of nodes.

at Forming a node as a sensor, this one indicates the sensor environment Detecting sensor head with downstream signal evaluation on. When forming a node as an actuator, this has an actuator unit (For example, a compressed air valve or a contactor) and a drive unit therefor on.

The Nodes each have a communication device, which contains the required radio transmitter and radio receiver to such a wireless Communication between the base station BS and the nodes (and vice versa) to enable. at a sensor passes the processed sensor signal to a modulator / encoder with downstream radio transmitter and antenna, where it connects to the base station BS is sent. With an actuator, this comes from a base station BS transmitted control signal via an antenna, a radio receiver and a demodulator / decoder to the drive unit.

The Base station BS is expedient to an automation device AD (Programmable Logic Control) connected and has a communication device on which sensor signals of the sensors and message signals concerning the current state of actuators (uplink, from node to base station) receives Outputs control signals for activation / deactivation of the actuators and signals for setting specific parameters of the actuators and sensors (downlink, from the base station to the nodes). The communication device of the base station BS has an antenna on, to which a radio receiver and a radio transmitter are connected. The signals of the radio receiver become is supplied to a demodulator / decoder and the radio transmitter a modulator / encoder upstream.

In 2 a cyclic TDMA frame is shown as used in the proposed system. Such a frame FR.1 is composed of N successive successive time slots TS.1, TS.2 ..... TS.n ..... TS.N, where
n = run index of a certain timeslot and
N = (total) number of time slots of a frame.

In this case, one or more time slots can be assigned to a specific node. For example, although the sensors generate their messages at random moments, a transmission adapted to the assigned timeslot or time slots occurs. To ensure that the information contained in a time slot is also assigned to the correct actuator, or To ensure that a sensor sends the information to be transmitted to the base station during the correct time slot, each time slot contains a typical synchronization word for exact synchronization between the base station on the one hand and the node on the other hand.

In 3 is a sequence of successive successive TDMA frames FR.1, FR.2, FR.3 ..... FR.m and frames, respectively, required for realizing a continuous signal transmission, where m is the running index of a particular frame is.

• • aus dem ersten Teil PR1 der Präambel, welcher zur Bestimmung des Gleichstromanteils dient,
• • aus dem zweiten Teil PR2 der Präambel, welcher die zur Synchronisierung zwischen Funkempfänger und Funksender erforderlichen Angaben umfasst,
• • aus der Symbolfolge der eigentliche Nachricht (Payload) PL und
• • aus einem Sicherheitsabstand (Guard Time) GT.

In 4 a time slot of a TDMA frame is shown. The time slot TS.1 is composed

• From the first part PR1 of the preamble, which serves to determine the DC component,
• From the second part PR2 of the preamble, which contains the information required for synchronization between the radio receiver and the radio transmitter,
• • from the symbol sequence of the actual message (payload) PL and
• • from a guard time GT.

Of the receiver the base station BS can be assigned from the each time slot Number unmistakable the respective radio transmitter, d. H. the relevant Determine node.

As already described above, results from the above System a problem if this once (at an earlier date) set Protocol (communication protocol) claims arising later the one to be transferred data length each input or output is no longer sufficient, for example, extended options covered, without, however, the underlying Modify structures of the protocol. For example, at an earlier specified Protocol for the symbol sequence of the message (payload) PL a data length of 8 bit for every input and for each issue has been scheduled. If these data lengths are for later use cases are not sufficient, it causes problems to increase the 8-bit data length. Definitely would it be in principle possible, a new protocol with increased data length for each input and Issue, but this measure would result in this newly created system incompatible with the previous system would. If the structures of the underlying protocol, however, despite extended Input / output capacity essentially unchanged stay, can except the former Nodes (with less requirement for the data length) simultaneously next to each other also newer nodes (with elevated Requirement for the data length) be operated in the same system. It is not advantageous then required, the earlier Exchange nodes for newer nodes.

• • Der Knoten muss fähig sein, in gleicher Weise wie zwei oder mehr separate Knoten während eines einzigen TDMA-Datenübertragungsblockes zu senden und zu empfangen, was erhöhte Ansprüche an die Dynamik von Sender und Empfänger stellt.
• • Ein Datenübertragungsblock muss mehr Zeitschlitze umfassen als Knoten innerhalb des Systems vorhanden sind.

According to the invention, with regard to the protocol, a single node acts in the same way as two or more different nodes in the data transmission, although it is still only a single physical unit, a sensor or an actuator. However, the prerequisites for this are:

• The node must be able to transmit and receive in the same way as two or more separate nodes during a single TDMA frame, which places increased demands on transmitter and receiver dynamics.
• • A frame must have more timeslots than there are nodes within the system.

As stated above, the protocol provides N timeslots per frame. There are I nodes, where: I <N.

each successful data transfer of a node must be confirmed by the receiver of the base station BS (and vice versa) by sending a receive acknowledge signal shortly after Data receipt is sent. For example, a node is in timeslot TS.n is active and transmits a signal, subsequently receiving the receive acknowledgment signal the base station BS in the time slot TS.n + 6 (or in both time slots TS.n + 6 and TS.n + 7) and has enough Time, in time slot TS.n + 16 (and possibly also in time slot TS.n + 32) also to be active. A limitation is just the default Number of time slots N of a frame (frame) represents.

The mentioned above Time slots TS.n + 6, TS.n + 16, TS.n + 32 are merely exemplary, because which in a system actually used, d. H. linked time slots depend on the time duration of a timeslot, of the performance of the node the data processing and the time period required is at a node from receive mode to transmit mode and to change vice versa.

• • einerseits eine genügende Zeitspanne für den Wechsel zwischen Empfangs-Betrieb und Sende-Betrieb und umgekehrt zur Verfügung stellen und
• • andererseits möglichst eng (zeitlich) innerhalb des Datenübertragungsblocks beabstandet sind.

The nodes are therefore assigned to each other associated time slots, which

• On the one hand provide a sufficient time span for the change between receive mode and transmit mode and vice versa and
• • on the other hand as close as possible (temporally) within of the frame are spaced apart.

• • können zwei unmittelbar aufeinanderfolgende Zeitschlitze miteinander verknüpft und einem einzigen Knoten zugeordnet werden,
• • kann das gemeinsame Empfangs-Bestätigungssignal – respektive zwei Empfangs-Bestätigungsteilsignale – für die in diesen beiden aufeinanderfolgenden Zeitschlitzen übertragenen Daten einem nachfolgenden Doppelzeitschlitz zugeordnet werden.

When dual-slot formats are used in the system instead of the single-slot formats discussed above

• • two consecutive time slots can be linked together and assigned to a single node,
• • the common receive acknowledgment signal - or two receive acknowledgment sub-signals - for the data transmitted in these two consecutive time slots can be assigned to a subsequent double time slot.

With in other words, the two reception confirmation signals occur for the individual Node as a common receive acknowledgment signal in a single Double time slot on.

For example is for a new node a data length 32 bit for one input and 32 bits for one Issue needed. This node is, for example, in the time slots TS.1 and TS.2 is active and transmits signals, subsequently receiving the receive acknowledgment signal the base station BS in the double-time slot TS.6 + 7, has enough time, in turn to be active in the time slots TS.16 and TS.17 (respectively Send signals) and subsequently receives the reception confirmation signal the base station BS in the double time slot TS.22 + 23.

The Using double time slots advantageously increases the bandwidth. The output data for a wirelessly remotely controllable nodes (actor) can be used together with the receive acknowledgment signal present in the same data package (i.e., transferred from the base station to the node in the same data packet become).

• • die Übertragungszeit minimiert und somit gut für geringe Interferenzen im System ist,
• • dazu verhilft, die Rate verlorener Telegramme zu verbessern (verringern), da lediglich eine geringe Datenmenge korrekt zu übertragen ist (lediglich die Hälfte der Datenmenge bei Vergleich mit einem Doppelzeitschlitz).

Unlinked time slots or data fields can be transmitted in the case of need (ie if, for example, a measured value change occurs in a sensor) with reduced data length, ie in a single-time slot (for example 8 bits), which is advantageous

• • the transmission time is minimized and thus good for low interference in the system,
• • helps to improve (reduce) the rate of lost telegrams, because only a small amount of data has to be transmitted correctly (only half the amount of data compared to a double-time slot).

Together linked Time slots or data fields (double time slots) can be used in in the same way in the form of the lower protocol levels be treated as unlinked data fields, since the knowledge of the connections between the time slots associated with a single node only in higher Levels of the protocol is required.

AD

automation equipment

BS

base station

Fr.1, FR.2, FR.3, FR.m

TDMA frame

GT

safety distance (Guard Time)

k

running Index a node

I

number the knot

m

running Index of the TDMA frame

n

running Index a time slot

N

number the time slots

PL

symbol sequence the message (payload)

PR1

first Part of the preamble

PR2

second Part of the preamble

S.1, P.2, p.3, p.4, p.k, p.k + 1,

S, K + 2, S.K + 3, S.K. + 4, S.I.

node (Sensors, actuators)

TS.1, TS.2, TS.n, TS.N

time slots a TDMA frame

Claims (4)

Method for operating a system with several nodes (S.1, S.2, S.3, S.4 ..... Sk, S.K + 1, S.K + 2, S.K + 3, S . k + 4 ..... SI) and a base station (BS) according to TDMA (Time Division Multiple Access), wherein cyclic TDMA frames (FR.1, FR.2, FR.3 ..... FR. m) and each TDMA frame is composed of successive consecutive time slots (TS.1, TS.2, TS.n ..... TS.N), characterized in that for the purpose of increasing the transmittable amount of data at least a certain node (S.1, S.2, S.3, S.4 ..... Sk, S.k + 1, S.k + 2, S.k + 3, S.k + 4. .... SI) at least two different time slots (TS.1, TS.2, TS.n ..... TS.N) are assigned. Method according to claim 1, characterized in that that between two time slots (TS.1, TS.2, TS.n ..... TS.N) a receive acknowledgment signal is generated. A method according to claim 1, characterized in that by using double time slot formats - two consecutive time slots are linked together and assigned to a single node, - the common receive acknowledgment signal for the data transmitted in these two consecutive time slots is assigned to a subsequent double time slot format. Method according to one of the preceding claims, characterized in that the linked time slots (TS.1, TS.2, TS.n ..... TS.N) on the one hand a sufficient Time span for the change between receive mode and send mode and vice versa to disposal and on the other hand as possible tight within the frame (FR.1, FR.2, FR.3 ..... FR.m) are spaced apart.