Arrangement having several functional units

摘要

PCT No. PCT/DE93/01185 Sec. 371 Date Jul. 20, 1995 Sec. 102(e) Date Jul. 20, 1995 PCT Filed Dec. 10, 1993 PCT Pub. No. WO94/14120 PCT Pub. Date Jun. 23, 1994The 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.