1. Field of the Invention
The present invention relates to a method and to a circuit arrangement for transmitting binary signals between peripheral units which are each connected at least to signal transmitters or generators, and peripheral units which are each connected at least to signal receivers, where all the peripheral units are connected to one another via a central bus line system, and are connected to a central control device which controls the signal transmission between the peripheral units and which comprises at least one central processor--in particular a micro-processor--with associated program memories and working memories, and a memory access device which is suitable for direct memory access.
2. Description of the Prior Art
In the context of the transmission of data information in a data transmission system it is already known, for example from U.S. Pat. No. 3,623,013, to control the actual data exchange between a central station, preferably a processor, and at least one of a plurality of data terminals which are connected as subsidiary stations to a common transmission path. In this case, the procedure is such that an address signal transmitted from the central station is compared with the address signals stored in the subsidiary stations. If identity is determined between the address signals which are compared with one another, a control signal which characterizes the availability of the particular subsidiary station is returned to the central station. This means that the data exchange between the individual subsidiary stations and the data terminals is carried out including the central station as a device which first receives and then retransmits the data. This represents a relatively elaborate data exchange procedure.
A teleprinter private branch exchange (PBX) is also known in the art, for example from German Application Ser. No. P 28 46 130.5, in which teleprinter subscriber stations are assigned to a communication unit and wherein, in addition to a central unit, there is also provided a storage unit. Here, the central unit serves to control the connection traffic between individual teleprinter subscriber stations with one another and possibly with one or more teleprinter lines or data lines of a separate teleprinter or data network. The signals which are transmitted from a teleprinter subscriber station or are transmitted thereto can be intermediately stored in the storage unit. In this teleprinter PBX exchange, the communication unit, the central unit and the storage unit are connected to one another via a common bus line system across which the data exchange between the individual units is handled. The handling of the data exchange takes place under the control of the central unit. In response to a pulse signal with which it is supplied by the communication unit, the central unit calls up in the communication unit the procedure which is to be carried out in order to forward the signals in question. This procedure can amount to a transmission of data in the relevant communication unit between the teleprinter stations which are connected to this communication unit.
Although in the case of the above-considered data transmission between teleprinter stations connected to the communication unit, the central unit, in practice, does not participate in the actual data transmission, the call-up of the procedure to be run in the communication unit means that data can only be transmitted in an agreed number between individual teleprinter stations and peripheral nits. Flexibility with regard to the scope of data to be transmitted, which on occasion is desirable, can only be attained by making available an appropriate number of procedures. This, however, entails a corresponding memory expense since the commands which form the individual procedures must be stored separately. Furthermore, such a process involves considerable dynamic loading in the running of the relevant procedures in the central unit.