História stránky

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Optimisation of old values processing coming from communication (automatically or as a result of TELL command GETOLDVAL) or values of remote tags (as a result of TELL command GETOLDVAL).
If the checkbox is checked, during processing of old value the archive database is queried whether the value is already present there. If it exists, the value is discarded (and recalcs of statistical or calculated archived values which use this primary archive value are not performed either).
Note: Optimisation is useful e.g. for archiving of I/O tags from communication using the protocol IEC62056-21:2002 File I/O. Its communication files contain several historical values (which KOM process sends as old values) and one new value for every I/O tag.

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• Periodical  - writing values into the archive is periodical. The archiving process in defined time moments stores the archive object value into the archive. Timestamp (the value time) is not given by the occurrence time of the archive object value, but by the time of the value storing into the archive.
  
  Reading the values stored periodically by means of D2000 system (ESL: GETARCHARR, GETARCHVAL, D2000 ObjApi: GetArchivData, D2000 VBApi: VBApiGetArchData, D2000 WorkBook) follows the rule that the archive object value out of time moments given by the period, is unknown (invalid). The result of the data reading is therefore given by the oversampling and the begin (BT) and end (ET) time as follows:
  • oversampling (step) = 0
    The reading results are all the values, time of which belong into the interval <BT, ET>.
  • oversampling (step) <> 0
    The reading result is the value array with timestamps continuously:
    BT+0*step, BT+1*step, BT+2*step, ..., BT+N*step.
    The number of values is given by the end ET of the time interval. The array value without a record with the same timestamps in the archive is invalid. The value with such a record is filled according to it. The above facts imply, that when reading periodical data, it is necessary (advisable):
    • to adjust BT exactly for some of the object archiving moments given by the period and time offset of the archiving.
    • oversampling value (step) must be an integer multiple of the archiving period.
    • ET = BT + (N-1)*step, where N is an integer number: the number of values in the final selection.
    
    Note: The statistical archive, from the reading point of view, acts periodically.

• Kotva
  sa_filter1 sa_filter1

  On value change - just value changes of the archive object undetected by the value filter are stored into the archive.
  
  Reading of values stored by using a filter by means of D2000 system (ESL: GETARCHARR, GETARCHVAL, D2000 ObjApi: GetArchivData, D2000 VBApi: VBApiGetArchData, D2000 WorkBook) follows the rule that the archive object value at any time (t) is given (equal) by the last historical value before the given time (t). The data reading result is therefore given by the oversampling and the begin (BT) and end (ET) time as follows:
  
  • oversampling  (step) = 0
    The reading result are all the values, time of which belongs to the interval <BT, ET> and 1 value before BT time, in case there is no value exactly equal with BT  time in the archive.
  • oversampling (step) <> 0
    The reading result is a array of values with timestamps continuously:
    BT+0*step, BT+1*step, BT+2*step, ..., BT+N*step.
    The number of values is given by the end ET of the time interval. The array value without any record in the archive with the same timestamp will be given by the last value before the time required.

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If the option Publish values is checked, then the historical value publishes its last archived value in the way, that depends on the object defined by the parameter Historical value as follows:

• For a simple HV - the object of Historical value type you are configuring gets the last value (if the parameter Historical value is not defined).
• When archiving an one-column HV - last archived values of individual items are filled into the relevant items of the column of a Structured variable type object defined by the parameter Target object.
• When archiving a structured HV - last archived values of individual items are filled into the relevant items of a Structured variable type object defined by the parameter Target object.

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