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Data backup apparatus utilized in an electronic control system and data backup method performed in the data backup apparatus

  • US 5,668,726 A
  • Filed: 12/16/1994
  • Issued: 09/16/1997
  • Est. Priority Date: 12/17/1993
  • Status: Expired due to Term
First Claim
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1. A data backup apparatus utilized in an electronic control system, comprising:

  • control data storing means having a first memory region, a second memory region and a third memory region for storing pieces of updated control data in the first memory region, storing pieces of previous control data in the second memory region and storing a checking value in the third memory region regardless of whether an electric power is cut off;

    control data copying means for copying the updated control data stored in the first memory region of the control data storing means to the second memory region of the control data storing means as the previous control data;

    control data, renewing means for renewing one after another the updated control data which are stored in the first memory region of the control data storing means and are copied to the second memory region of the control data storing means, by the control data copying means on condition that the electric power is supplied to the control data renewing means, the renewal of the updated control data being stopped during the renewal by cutting off the electric power supplied to the control data renewing means in the middle of the renewal;

    checking data setting means for setting a piece of first checking data indicating a start of the renewal of the updated control data performed by the control data renewing means to the third memory region of the control data storing means in cases where the updated control data stored in the first memory region of the control data storing means is renewed by the control data renewing means, and setting a piece of second checking data indicating a finish of the renewal of the updated control data performed by the control data renewing means to the third memory region of the control data storing means in cases where the renewal of the updated control data performed by the control data renewing means is finished, the storage of the first checking data is maintained in the third memory region of the control data storing means in cases where the electric power supplied to the control data renewing means is cut off in the middle of the renewal performed by the control data renewing means; and

    control data returning means for returning the previous data copied to the second memory region of the control data storing means by the control data copying means to the first memory region of the control data storing means as the updated control data in cases where the electric power cut off is again supplied to the control data renewing means on condition that the storage of the first checking data is maintained in the third memory region of the control data storing means.

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