Abstract: A system having several active (master) and passive (slave) bus users (processors), each of which is allocated a memory with its own memory area. Each bus user has read access to its own memory area and each active (master) bus user has write access to every memory area. A control line is provided for sending a control signal which indicates to the active (master) bus users accessing the memory areas whether data have already been written into the memory areas. The control signal has dominant and recessive states. Outside of the access cycles, all bus users generate a dominant state. During a cycle of access to memory areas, only the bus users in whose memory areas the data have not yet been written, generate such a signal. The system may be used in automation systems.

Abstract: The invention relates to an arrangement for running a system bus in a device such as a programmable controller. The arrangement includes a number of card slots interconnected via a system bus with data and control lines, and via address lines. A number of functional units may be plugged into the card slots. One or more of the functional units may be adapted for read and/or write access (e.g., a CPU component), and each functional unit so-configured includes an arbiter capable of managing the system bus. At system startup, one of the arbiters is activated to manage the system bus while the other arbiters remain passive. The functional units may advantageously be plugged into any of the card slots; that is, there is no need to have a particular card slot dedicated to running the system bus.

Abstract: A configuration for data transfer with a parallel bus system including an address bus, a data bus and a control bus and with several units interfacing with them. A first control line is used to send an acknowledge signal with which one or more units addressed by a first unit acknowledge accesses in access cycles. A second control line is used to detect addressing errors and accesses to non-existing units and to carry a signal ready control signal to the first unit from the others indicating whether one of the interfaced units was addressed. To do so, the signal ready control signal has dominant and recessive states. During an access cycle, only addressed units generate a dominant state. The control signal is also used for synchronous multipoint access. The invention can be used in bus systems.

Abstract: An arrangement for transmitting data over a bus (2, 6, 7) has a central unit (1, 4, 5) which initiates data transmission and one or several peripheral units (3, 8, 9) linked to each other by the bus. In at least one of the components, besides first control lines and data lines for transmitting a data word having a first data width, further control lines and further data lines for transmitting a data word having a second data width are also provided. These are designed in such a way that components with different data bus widths can communicate with each other by transmission of data words having the smallest existent data width. In automation equipment, the invention allows any combination of components of different classes of capacity.

Abstract: An arrangement with a plurality of plug points which are interconnected via a system bus having data and control lines, address lines taken to connections of the plug points, one of which is connected to a selector terminal, and plug-in functional units, at least one of which has contacts for connecting the address lines to this unit and each of the remaining functional units has contacts for connecting the unit to the selector terminal of the plug point. Units performing read and write functions can be fitted at any plug point in such an arrangement. The invention is applicable in store-programmable controls.