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PLC data log module with backup function

  • US 9,817,590 B2
  • Filed: 09/11/2015
  • Issued: 11/14/2017
  • Est. Priority Date: 10/06/2014
  • Status: Active Grant
First Claim
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1. A programmable logic controller (PLC) data log module with backup function configured to generate a log data based on a PLC CPU'"'"'s device value collected when a set condition is met and to transmit the generated log data to an external memory, the PLC data log module comprising:

  • an internal memory configured to store the log data and to transmit the stored log data to the external memory;

    a backup memory configured to back-up the log data transmitted from the internal memory to the external memory and to store the backup data; and

    a controller configured to;

    determine whether the PLC has been reset or if the PLC has been changed to a turned-on state from a turned-off state;

    transmit the backup data stored in the backup memory to the external memory when it is determined that the PLC has been reset or that the PLC has been changed to a turned-on state from a turned-off state;

    read data of a predetermined size stored in the external memory starting from a last point of the data stored in the external memory when all of the backup data has been transmitted to the external memory;

    determine whether bad data is included in the data of the predetermined size read from the external memory; and

    delete data positioned between data determined to be bad data and a last point subsequent to the position of the bad data and substitute the deleted data with a null value.

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