DE19510280A1 - Exchange protocol for digital data - Google Patents

Abstract

A packet communications network 10, 12 connects two or more control devices 14, 16, 18 and 20 in a home electrical management system. The digital data exchange protocol comprises the use of Carrier Sense Multiple Access/Collision Detection protocol (CSMA/CD as shown in figure 2), having an additional frame (figure 3) in the packet to initiate a TDM communication period during which the status of each device can be transmitted to each other device connected to the network. The protocol allows the flexibility of CSMA/CD to be used while using the speed of the TDM frame to gain status information. <IMAGE>

Description

The invention relates to electrical management or mana gement systems for households and buildings and in particular a communication protocol suitable for such systems.

A typical electrical control system for Household and building installations include a number of Devices for control switches, sockets, elec trical loads of various types, such as. B. lighting, Heating, cooling, for various devices with a motor drive, and for protective devices such. B. Breakers for miniature circuits, residual or fault current breakers, Fuses, etc. are designed. A tax system in such a way an installation comprises one or more transmit / receive Low energy facilities, which one or associated with several of the above-mentioned electrical elements are net, with the transceivers typically having a Communication medium are connected in parallel.

Because of the simplicity and cost, the communication includes tion medium typically a two-wire energy and Datagram or signal device. The two-wire set-up Tung can be with a shielded or with a non-shielded shielded twisted pair cable. It can different topologies such. B. that of a bus, a star, a ring, a grid, and / or one Mixture of the topologies above, used with this medium become.  

Each device in the network includes a transceiver for receiving and sending data signals, a compu The facility to depend on data on its own initiative of programs stored in it send, a storage device to various data, e.g. B. the status of other facilities in the network and a control circuit device for Control of associated electrical devices, such as. B. Lighting, switches or loads.

Every device in the network is designed and arranged, Da exchange signals via the two-wire medium. By Connecting the different facilities it is possible the various devices assigned to each facility control and manage, each one from the other un is controlled dependent.

The exchange of information between the institutions is an essential element in the control of the setup in the network, and the exchange of information in digital form is typical. Digital signals can trained to exchange information errors minimize what is essential in safety-critical environments is. However, the communication medium has an in inherent upper bandwidth for the amount of digital informa tion which it can carry at any time. That's why there are a number of digital transmission methods which for the best possible use of the available Range of the medium between the numerous and ver different types across the network of facilities can be used. The ability of communication mediums, digital information on all facilities transmit, can also be entered by its total length be limited because the transmission time of digital signals from the most distant facilities  the allowed period of time in which digital signals do not overlap in time.

A known as time division multiplex method and called TDM Procedure allows each facility to stand in a row to alternate method, with each facility being regular the total data exchange bandwidth for a predetermined one Time span. When using this procedure is the transmission time between the facilities is clear segmented and each time segment is entered by only one only facility within the network During this time, all other facilities the network from the sending device to ver read provided data. A TDM procedure is required assigns a unique time channel to everyone existing and / or future facility, and the An catch and the end of each time channel are in one Network localized master clock synchronized.

All devices carry a predetermined one after the other Share of digital information until each facility sent their data. This is an advantage sticky and especially efficient if a frequent act alize the data either through a central tax unit or is required by each institution itself. In a network where each Setup the operating mode or operating condition whose facilities are known in the network, TDM (Time Division Multiplexing) a device for the orderly Exchange of information. However, this arrangement is very inflexible and can the amount and sometimes the complex xity of the data transmitted by each facility restrict.  

A limitation of the TDM method is that at any time channel of all communicating institutions unequivocal must be interpreted. A central, synchronizing Clock can over each period of data exchange Initiate transmission, but from signal propagation delays Delayed digital signals resulting along the network Data becomes lost or falsified to lead. The receiving facility is not simply being can agree which bits of data from which data records originate, and so no data can be received from the recipient be accepted safely. This is why TDM is not ideal for long or extended network distances.

Another communication method for digital data in such networks is a method of protecting against that multiple transmitters in a network simultaneously the, this method CSMA / CD method (Carrier-Sen Multiple Access / Collision Detection) and usually used when data on a of many, widely distributed over a large network directions must be transmitted. Another verb The CSMA / CD scheme is a method of avoidance of collisions or collisions, CA (Collision Avoidan ce) called, so that the inevitable get together collision of information packets of digital data and its Frequency reduced or if data as a result of a Collision are lost, can be recovered can.

The CSMA / CD-CA process does not require any central coordination dination, so it is for an electrical control system for household and building, which is relatively high exchange advise digital data for information transmission between widely distributed, intelligent facilities such as the described above, needed, is well suited.  

However, in a bandwidth-constrained network the use of, for example, a type of the above wrote the CSMA / CD method necessarily optimal for the rapid absorption of In formation of a large number of facilities confi guriert. As the communication between the facilities individually and during each such communication period only one can be built at any time Send unit. The CSMA / CD process is therefore an in efficient method for the exchange of status information between a variety of facilities.

The invention is based on the object Exchange protocol for digital data when in use in a communication network in data packet mode for the connection between two or more control devices to accomplish.

The object is achieved in that a generic exchange protocol for digital data with the characteristic features listed in claim 1 is created.

An exchange protocol according to the invention for digital data involves the use of a method of protection against that several sending devices in a network at the same time send which CSMA / CD method is called and which has an additional data block, which is designed is a communication period of time division Start procedure, in the course of which the status of everyone Setup to any other connected to the network NEN facility can be transmitted.  

In an exchange protocol according to the invention for digital The CSMA / CD protocol uses a process for data Prevention of collisions, which is called CA.

In an exchange protocol according to the invention for digital Data is kept during a communication period of time Time-division multiplexing the time channels for each facility by a single clock, on which the network reference, synchronized.

In an exchange protocol according to the invention for digital Data is the time slot's communication period plex process greater than the propagation delay between entities that, measured over the network, are physically the most separated.

The invention will be described in more detail below with the aid of the drawing explained; in this shows:

Figure 1 shows a basic design of a plurality of devices arranged in a network, which are connected to one another by a pair of lines.

Fig. 2 is a timing diagram of a transmission block of digital data according to the CSMA / CD-CA method;

Fig. 3 is a block initiating data transmission by the TDM method for a data block according to the CSMA / CD method, and CA

Fig. 4 is a diagram of a data exchange protocol in accordance with the TDM method according to an embodiment of the invention.

A wide variety of information, tax and administration systems, which communication networks in the data packet Operation with two-wire supply and communication me making service usable are just as diverse used by applications. In particular, networks in the Data packet operations much more common by the construction industry used in residential, commercial and industrial buildings to To maintain building, control and management systems.

Conductor pairs are typically simply installed and switched in new and already existing buildings, and simple, pluggable line connections, as shown in FIG. 1, can be connected at any point along the conductor pair. Lines 10 and 12 provide the medium for the transmission of power and signals to devices 14 , 16 , 18 and 20 , which are distributed along lines 10 and 12 as necessary.

In this embodiment, the exchange protocol for digital data can preferably be of the CSMA / CD-CA type, of which FIG. 2 shows a typical data transmission block, the control block being zero in this example: CONTROL = 0. If necessary, however, one can be specific frame, as shown in Figure 3, where the control block is not identical zero, is sent from each device in the network to start a TDM communication period.

During the TDM period, all participants can Facilities preferably through this special da transmission block and / or by a synchro nising clock, which at all times on the comm communication medium is available to be synchronized. Of the synchronizing clock generator provides only one temporal reference and can therefore not by "  intelligent "clock facility, which is somewhere in the network is localized.

Preferably, a communication protocol that the CSMA / CD and / or the CSMA / CD-CA process with a star TDM frame used in its out design a predetermined maximum bandwidth and a maximum physical length of two-wire communication mediums on. Predestination of these two characters ristika reduces the likelihood and / or did physical occurrence of errors in the time sequence, which can occur if one of the two exceeds will.

It is also for all connected facilities desirable that this with the received data transfer block, which the TDM time period for the exchange di gitaler data starts, the TDM data transmission synchronization maintain.

Furthermore, it is advantageous that the starting data frame of the TDM protocol period demanding facility contains sufficient information to to enable the participating institutions to take appropriate measures Information within this TDM frame Period.

In this embodiment, the TDM frame period is typically used by all devices on the network to collect information from all other devices currently working on the network, as depicted in FIG. 4. The type of information that can be provided includes the status of one, all devices in the network, alternatively groups of devices in the network, or even the existence of a device newly added to the network. A list of all active facilities can either be kept centrally available or distributed among all facilities. The simplifies and supports the identification of ongoing and possible communication and problems of recruitment between the institutions.

Using a specialized TDM data transmission block period for quick exchange of informa tion mainly within a CSMA / CD-CA protocol ensures that important information quickly and, wich tiger even more efficiently between each facility is exchanged. A conventional CSMA / CD-CA communication protocol takes multiple, not necessarily, it successful communication attempts when sharing similar information among the facilities of the network work is needed, takes longer and uses the sometimes narrow bandwidth.

Since each frame of the CSMA / CD-CA protocol will be confirmed when received as correct the status of the device connected to the facility or have changed the load as needed. Consistently becomes information which during any one at a time started TDM frames was collected, also a change in the operating status of the starting or Confirm sending institution.

This preferably uses a TDM data transmission Grant block period in a CSMA / CD-CA protocol does a reduction in the number of retransmissions which, when exchanging information after a CSMA / CD-CA protocol would typically be necessary. This  has particular advantages in the typically low Communication rates of two-wire communication media, which are used in building management networks.

The invention was made on the basis of a specific network Packet operation described, which both CSMA / CD-CA- as TDM communication protocols are also used to ensure effi efficient use of the available bandwidth to reach.

However, one of ordinary skill in the art is aware that the inventions application in their use not to the described applications is limited and that the invention in its drafting design neither in relation to the special Components still related to the configuration of the elements te of the protocol, as described here, be is limited. It can be seen that different modes fications can be done without the prince pien deviate from the invention, therefore the inven be understood to include all of these modifications includes.

In summary, the invention therefore relates to electrical management and management system for home stop and building and especially one for use suitable communication protocol in such systems.

A typical electrical control system for household and Building installations include a variety of facilities conditions for control switches, sockets and electrical Loads of different types are designed. A control system stem in such an installation comprises one or more Transceiver devices with low power consumption me, which with one or more of the above elec trical elements are assigned, the transmission  Receiver typically over a communication medium are connected in parallel.

Networks in data packet mode are used particularly frequently by the construction industry for residential, commercial and industrial buildings the used to building, control and management systems to support. Wire pairs are typically one installed in new and existing buildings and connected and simple line connections are to everyone Point can be connected along the pair of conductors.

The invention disclosed herein includes an exchange protocol for digital data for use in a communica tion network in data packet mode for the connection of two or more control devices which use a method of protecting against multiple broadcasts Send directions in a network simultaneously, CSMA / CD-Ver drive called, in data packet operation, which includes a contains additional frame in the packet to star a time division multiplex communication period in which the status of each facility to each transmitted to another device connected to the network can be.

The exchange protocol of digital data can be a CSMA / CD Protocol with a collision avoidance procedure, Use the CA procedure. The exchange protocol for digital data is such that the time division multiplex nication period is greater than the spread delay between the facilities which, via the Network measured, are the most distant from each other.

Claims (4)

1. Exchange protocol for digital data for use in a communication network in packet mode for the connection between two or more Steuereinrichtun gene, characterized in that a CSMA / CD data packet operation protocol (Carrier Sense Multiple Access / Collision Detection) is used, which an additional data transmission block which is designed to start a time-division multiplex communication period in which the status of each control device can be transmitted to any other control device connected in the network. 2. Exchange protocol for digital data according to claim 1, characterized, that the CSMA / CD protocol is also a collision avoidance system (CA, Collision Avoidance). 3. Exchange protocol for digital data according to one of the previous claims, characterized, that during the time division multiplex communication time average the time channels for each control device a single clock on which the network is based works related, can be synchronized.   4. exchange protocol for digital data according to claim 1, characterized, that the time division multiplex communication period is greater than the propagation delay between Control devices, which, measured over the network, are physically the most distant from each other.