Real Time eXecutives, Inc. Historical Database Concepts
STORING LARGE AMOUNTS OF DATA FOR VERY FAST RETRIEVAL ON THE LAN/WAN
Often the use of relational database, or transaction-oriented technology, for off process historical LAN/WAN database applications, will not meet the unique needs of doing unconventional operations on data. As an example, for situations that require storing a large volume of time series data and then retrieving the data very quickly, the "one-size-fits-all" solution does not work very well. It is in this area of off process historical data warehousing and retrieval that the RTXHDB (RTX Historical Database) system excels. RTXHDB processes and stores a massive flow of data for LAN/WAN database applications, which then can be retrieved with a great deal of speed and quickly turned into useful information for the PC user.
PROVIDING DATA WHILE MAINTAINING SECURITY ON THE LAN/WAN
One major problem faced by System Managers is how to provide Information Users access to all of the data produced by process computers, while maintaining system security. When process computers used proprietary operating systems, this issue did not pose a threat to system integrity. However, with the introduction of "Open-Systems", there are more threats to system integrity, should someone inadvertently corrupt some files on a process computer, while using that "Open-System".
One solution is to introduce a Firewall router between the process computers and the plant network. Such devices impose restrictions based on a user's address, protocols, ID and password, or some combination of these. This approach is still not ideal. It can either deny access to the very data that the System Managers wish to deliver to their users, or allow almost free access, thereby becoming nearly transparent and ineffective. Also, routers are very expensive pieces of equipment when purchased fully configured, or they require a great deal of time and specialized knowledge to set up.
The Secure RTXHDB SYSTEM ARCHITECTURE
RTXHDB offers a simple, secure alternate solution to Firewall routers by allowing a variety of multiple process data sources to be combined and connected to a Local Network Segment through a RTX Gateway, thus isolating it from the Plant Administration or Engineering Network. The RTX Gateway's only function is to extract data from these multiple sources of process information and reorganize in a format for storage in the RTXHDB Data Server Workstation. After storing the process data in an RTXHDB Data Server Workstation, all of the plant users can enjoy access to the process data. This is all happening while not allowing access to the actual Process Computers. The following diagram shows how this can be accomplished:
|The Secure RTXHDB System Architecture|
Each end-user PC has high speed, easy-to-use access to the RTXHDB Historical Databases through the RTX provided TL ActiveX for RTXHDB, Report Builder for RTXHDB, OPC-HDA Server for RTXHDB, RTXHDB Automation Server, Watchdog for RTXHDB, or other Windows applications.
SYSTEM FUNCTIONAL DESCRIPTION
The RTXHDB system software packages run on the Process Computers, the RTX Gateway, RTXHDB Data Server Workstation and end user PCs attached to the Plant Administration or Engineering Network LAN.
RTXHDB system software collects current values of process variables in the Process Computers based on time slots that typically range from 1 second to 1 hr. The current values are then automatically transmitted to the RTX Gateway by way of a Local Network Segment. These current values are then stored in the RTXHDB Data Server Workstation for review by different users. Once sets of current values are collected, no further accesses to the Process Computers are necessary.
The RTX Gateway is an ordinary PC attached to the Process Computers by way of a Local Network Segment. This Local Network Segment uses standard network topologies and protocols or if needed a Serial communications link. Operating on the RTX Gateway, RTXHDB system software automatically builds a historical database of current values on the RTXHDB Data Server Workstation and provides isolation from the Plant Administration or Engineering Network.
The RTXHDB Data Server Workstation holds the historical databases). It provides a Direct Link (DLL), OPC-DA, OPC-HDA for historical information to other Windows applications. Besides the current value database, RTXHDB can automatically build any number of propagated databases using the following algorithms: average value, standard deviation, maximum value, minimum value. Typically the averages are 15 min, 1 hr, one shift, one day, and one week. These databases can be as large as the RTXHDB Data Server Workstation can hold. If needed, portions of the database's) can be archived, onto such media as DVD or CD-ROM's or magnetic tape, providing unlimited off-line storage of historical data that can easily be brought back on-line.
All users of the LAN/WAN simply access the RTXHDB using any of these RTX provided powerful tools:
|Database can be scanned quickly||-||Reduces time for problem searches.|
|Data can be collected from a variety of process sources||-||Allows a comprehensive, consolidated database to be built for the plant.|
|Large amounts of data (many years) can be stored||-||Data collected over a long time can be analyzed.|
|Specific tags can be monitored and cross referenced on the same screen||-||Specific interactive conditions can be analyzed on the same screen.|
|Data can be studied in privacy of own office||-||Highly secure environment with no interference in regular control room work.|
|Data can be easily imported into spreadsheets||-||Additional graphs and numerical analysis are possible.|
|Data files are read-only||-||Records cannot be changed or altered.|
|Evidence for validation is documented||-||Review and inspection are easily available to outside agencies.|