| 摘要 |
1,108,540. Computer control systems. FOXBORO CO. 8 Sept., 1966 [29 Sept., 1965], No. 40259/66. Heading G4A. In a computer system for controlling an industrial process and involving the use of two or more computers, on failure of a first computer, some at least of the control functions performed thereby are taken over by a second computer. In the embodiment shown (Fig. 2), a first direct digital control computer 1 is connected in parallel by a bus 3 to input/output modules, comprising, for example, a solid state valve output module 8, a data input multiplexer 9, an operator's console 10 with display 36 and a pulse counting module 15. A second supervisory computer 2 is likewise connected in parallel by a bus 20 to supervisory function modules comprising for example a typer control 37 and data entry and display modules 38, 39 for input and output of data from supervisory and engineer's consoles 40 and 41. Each bus 3 and 20 includes a system check module 43, 34 respectively for checking the functioning of the associated computer. On detecting abnormal conditions, the corresponding data bus transfer switch 31 or 32 is operated to connect both buses to that computer which is still functioning normally. Interrupt signals on lines 43B or 44B are also issued whereby a stand-by programme for dealing with the situation may be called-in from a disc store 29. The two computers may communicate by way of a module 21. In a simplified embodiment (Fig. 1, not shown), a single system check module is included in bus 3 so that only the control computer 1 is provided with back-up facilities. The input/output modules differ also. In the embodiment of Fig. 3 (not shown), involving two direct digital control computers, back-up facilities are provided in respect of only those control loops controlled by the two valve output modules which are critical. The embodiment of Fig. 4 (not shown) is similar with the addition of a third supervisory computer. |
