The KOM Archive function is the function of process functionality enables the D2000 KOM that allows process to work in the offline mode (no connection to process the D2000 Server process) and to save values acquired from communication into a file (archive) for their later transmission into the D2000 system.
This functionality enables a remotely running D2000 KOM process to avoid losses of communication data losses :
- in case of network disruption between between the D2000 KOM and the D2000 Server processes
- in case of failure of the D2000 Server process or the entire application server
- in case of D2000 upgrade
Process D2000 KOM with the function KOM Archive may be started with parameters The KOM Archive functionality for the D2000 KOM process is activated by /KA<ArchivSize> and /KX command line parameters. The parameter /KA KA parameter enables the KOM Archive function functionality and the parameter ArchivSize is the size of the archive file in megabytes (between 1 up to and 400). The parameter /KX parameter enables the operation of process the D2000 KOM process after a loss of the communication with the D2000 Server. The An optional parameter /KM defines the method for sending values from the KOM archive after connection with the D2000 Server is established.
Process The D2000 KOM process with the function KOM Archive functionality can be also run started without process the D2000 Server running process. In that case, the configuration is loaded read from the a file, that is placed in the subdirectory \KOMARC of the application directory. The subdirectory is created automatically after running process the D2000 KOM process with the parameter /KA. Besides the above-mentioned parameters, there is also the parameter the /KC<ApplicationName> <ApplicationName> parameter required for the definition of the location of the configuration file.
Condition A necessary condition to run process the D2000 KOM process without process the D2000 Server process is the existence of the configuration file. The file is created and updated automatically after connecting process the D2000 KOM process is connected to process the D2000 Server process. The file is updated after each change of child objects (lines, stations, I/O tags) that belong to a specific D2000 KOM process.
Use of KOM Archive in redundant systems:
Communication between D2000 KOM processes in redundant systems has not yet been implemented, so their use is limited. The D2000 KOM process, which starts without the D2000 Server process, is automatically HOT (i.e. there is a possibility of a collision of several HOT D2000 KOM processes).
A partial that belong to given process D2000 KOM.
A particular solution (working while at least one process D2000 Server process is in the system) is to run process the D2000 KOM process in the "shadow" mode (the parameters /RD<GroupName> and /W<MyName>,<MyNumber>)
Example:
KOM nr.1: kom /RDmy_group /Wself,1 /KCmy_application /KX /KA100 /TP
KOM nr.2: kom /RDmy_group /Wself,2 /KCmy_application /KX /KA100 /TP
Processes The D2000 KOM, started processes started in this way , are connecting to the HOT server. One of them is active and the others act other one is passive - it acts as if it was connected to the STANDBY server D2000 Server. After the current server drops out or it is switched, processes D2000 Server becomes unavailable or STANDBY, the D2000 KOM processes attempt to connect to the a new HOT server. When all servers drop outare unavailable, processes the D2000 KOM processes stay in the status same state as they were before drop-out the D2000 Server became unavailable (one is HOT active and the other STANDBYone is passive).
A problem can occur, when something happens to the HOT process active D2000 KOM drops out process (the other process D2000 KOM process is not notified and stays in the STANDBY state STANDBY till it is connected reconnected to serverthe D2000 Server).
Another problem is starting process the D2000 KOM process when no server exists - process the D2000 KOM process is automatically transferred into the HOT active state as mentioned above.
...