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Archive file
The KOM Archive file together with containing the saved values is named "KOMARC.KCD" and it is placed in the application subdirectory \ KOMARC. \The KOMARC directory is created automatically if needed. The KOM Archive functions as a circular buffer so that values are saved in the buffer regardless of the fact that process when the D2000 KOM process is in online or offline mode. The oldest values are rewritten by the current new ones. The buffer is common for al all objects, which means that is not divided for the individual I/O tags, but all incoming values of I/O tags are written in the sequence as they came.
The archive file is divided into the header (at the beginning of the file) and blocks with saved values. The header contains information about blocks of values (number of written values, write times,...). Each block with data allows to save cca a saving of about 1500 values. Number The number of block blocks is limited by the file size (parameter /KA). Each block is protected by check suma checksum. Block writing onto the disk is performed only in case of its being when it is full or after the a timeout (1 minute) has elapsed. Values saved in offline mode are specially labelled labeled and sent into the D2000 system after establishing a connection to process the D2000 Server process.
Data reading
According to the parameter Based on the value of /KM<ArchiveMode> parameter value of process the D2000 KOM process, a mode of sending values from the buffer into the D2000 system , will be determined. The value of the parameter ArchivMode may be:
- 1 - (implicit value) for automatic sending of values after starting process the D2000 KOM process (if any values acquired in the offline mode are found in KOM Archive) or after reconnection to Server (values acquired while process the D2000 KOM process operates in offline mode).
- 2 - values are sent only when requested - by the Tell command READKOMARC.
Log fileLogfile
Together with "KOMARC.KCD", "KOMARC.LOG" will be created in the same directory. Into it, there are written in the text form It is text-based and it contains the following information stored together with the time and date of creation:
- Information about the file generationcreation,
- Errors Information about errors during KOM Archive functioning (incorrect check sumschecksums, errors of system callingscalls, ...).
- Executed transactions of Information about performed data reading transactions (transaction type, read-out data interval, ...)
Possible risks
Data writing into KOM Archive loads minimally puts a minimal burden on the operating system (minimal disk operations, most operations are executed in the RAM). It Sufficient free disk space is necessary to keep the disk space free for for the creation of the archive file generation. It is generated created immediately with the required size (parameter /KA) and its space size will not be changed later.
A problem may occur in ArchivMode mode 1 mode, if more data too many values are being sent into the D2000 system and the D2000 Archiv is consequently overloaded and its functioning is hindered. Another problem may occur when process the D2000 Archiv process is not running while sending values from process the D2000 KOM process. In such cases, we recommend to switch KOM Archive to ArchivMode 2 mode and switching the ArchivMode mode to 2 and to control the KOM Archive reading via a special event using the Tell command READKOMARC. The event should solve handle the listed abovementioned problems, e.g. monitoring of the D2000 Archiv process monitoring, a batch reading of the KOM Archive reading and , the D2000 Archiv load load monitoring, etc.
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