Abstract: The harsh environment of offshore oil production underscores the importance of alarm limits for control parameters in the DCS system of offshore platform water treatment. Improvements in offshore injection and production processes, as well as equipment upgrades, inevitably lead to changes in these alarm limits. This paper utilizes the embedded VBA language of the RSView32 configuration software, combined with network and database management technologies, to study and implement online management of alarm limits for control parameters in the platform water treatment DCS system. Long-term system operation has demonstrated the feasibility and practicality of this method. Keywords: RSView32; DCS; Alarm; Data Management; ADO Abstract: The abominable environment of petroleum production on the sea results in the importance of alerting the critical value of industrial control parameters in the platform seawater treatment DCS. Improvements in the petroleum production process and equipment updates bring about changes in the alerting of critical values ​​in the platform seawater treatment process control system. This paper integrates the capabilities of VBA embedded in RSView32 configuration software with Network and RDBMS to research and realize the online management of altering critical value industrial control parameters in the platform seawater treatment DCS. The system's long-term operation proves that the online management method is feasible and practical. Key words: RSView32; DCS; Alerting; Data Management; ADO With the rapid development of measurement and control technology, distributed computer control systems (DCS) have been increasingly widely used, and the adoption of computer monitoring systems to achieve integrated automated production in offshore platform oil production is becoming increasingly common. Due to the harsh marine production environment, equipment is prone to corrosion and aging, resulting in a high failure rate. Therefore, the DCS system must possess robust self-diagnosis and safety protection functions. When unforeseen interferences and malfunctions occur during production, the system must react promptly and issue alarms. The industrial control data collected by the system forms the basis for diagnosing and resolving these faults. Therefore, the alarm limits corresponding to each industrial control parameter within the DCS system play a crucial role in the safety and reliability of the entire oil production process. Furthermore, technological advancements inevitably drive continuous improvements in platform oil production processes and upgrades to production equipment. Consequently, the alarm limits for each industrial control parameter must be appropriately modified based on new processes, equipment, and process requirements. Therefore, the DCS system must effectively manage the alarm limits for industrial control parameters. Currently, DCS system development often utilizes configuration software that offers high reliability, flexible configuration, and ease of application program generation. In most cases, system developers set specific upper and lower alarm limits for each industrial control parameter based on the operational status of the production process during system development. When the alarm limit of a certain industrial control parameter in the system needs to be modified, developers usually revert the DCS system to the editing state of the system development configuration software before modifying the alarm limit of that industrial control parameter. This prevents the monitoring system from monitoring the industrial control process in real time during the period when the alarm limit of that industrial control parameter is modified. If an abnormality occurs in the industrial control process during this time, it will have a certain impact on production. Therefore, realizing online management of the alarm limits of industrial control parameters is of great significance to the safe operation of offshore platform oil production. 1. Composition of the Platform Water Treatment DCS System The lower-level computer of the platform water treatment DCS system uses two sets of AB's SLC500 PLCs. One set is used for process control of the seawater fine filtration backwashing sub-process, and the other set is used for data acquisition and control valve opening adjustment of pressure, temperature, flow rate, liquid level, seawater oxygen content, and seawater turbidity in other sub-processes (as shown in Figure 1). The upper-level monitoring computer is responsible for process monitoring of the water treatment process, realizing real-time display of data acquired by the PLCs, trend depiction, and dynamic simulation of the entire process. The data management computer is primarily responsible for managing personnel, equipment, and industrial control data, while also providing report printing and data query functions. It also possesses the same monitoring capabilities for the industrial control process as the monitoring computer. Communication between the upper-level monitoring computer and the PLC utilizes a DH+ industrial LAN, while communication between the monitoring computer and the data management computer is achieved via Ethernet. The upper-level monitoring system is developed using Rockell RSView32 configuration software, the data management server uses Microsoft SQL Server 2000, and the data management system is developed using Microsoft Visual Basic 6. 2. Specific Implementation of Online Alarm Limit Management : In RSView32 configuration programming, the Tag is the core of the programming and has two data source types: Device and Memory. A Device-type Tag can be considered as data from an external device, synchronously updated with a memory address unit of the lower-level PLC. Therefore, data communication between the upper-level and lower-level computers is achieved through Device-type Tags, and each monitored industrial control parameter corresponds to a Device-type Tag. In addition, the data source type of the Tag is Memory, which can be understood as data from inside the computer and can be called a variable. The online modification of the alarm upper and lower limits of the industrial control parameters is achieved by operating on the Tag of the Memory type. 2.1 Basic idea (1) In the Tag Database of the RSView32 project manager, the alarm limit of each detected industrial control parameter is set as a Tag (variable) instead of a specific value. Its Tag type is Analog, its Data Source type is Memory, and its Initial value is set to the limit value required by the current process. The creation of public variables (Tags) is shown in Table 1. PublicTag—Returns the name of the industrial control parameter Tag whose alarm limit needs to be modified; UpperLimit—Returns the name of the Tag corresponding to the upper limit of the industrial control parameter alarm; LowerLimit—Returns the name of the Tag corresponding to the lower limit of the industrial control parameter alarm. (2) Use Microsoft SQL Server2000 Database Manager to create the AlertingValue database and configure a DSN pointing to the AlertingValue database in the ODBC Administrator of the operating system control panel. Create a free table named AlertingTagValue in the database AlertingValue to store the current value and related attributes of the Tag for alarm upper and lower limits of each industrial control parameter, as shown in Table 2. (3) Use the embedded language of RSView32—VBA and the remote data access technology ADO to operate the alarm limit database, realize the management operations such as querying, modifying and storing alarm limits, and realize the effective management of alarm data. 2.2 Technical Implementation and Program Design (1) In the Visual Basic Edit of the RSView32 project manager, create the form frmAlertingV for online management of alarm upper and lower limits, as shown in Figure 2. Table 3 shows the properties of the relevant controls in the form frmAlertingV. (2) Set a Touch action for each industrial control parameter with an alarm limit in RSView32 to return the name of the Tags corresponding to the industrial control parameter and its alarm limit: Taking the "liquid level display" of the corrosion inhibitor 1# dosing tank as an example, add the "Touch" action as follows: & Set PublicTag “LT-2C2101” ; & Set UpperLimit “H_LT-2C2101”; & Set LowerLimit “H_LT-2C2101”; VbaExec frmAlertingV.Show (3) Program design a. Define public variables Public cn As New ADODB.Connection Public rs As New ADODB.Recordset Public Upper As String Public Lower As String b. Create a connection with the SQL Server database AlertingValue cn.ConnectionString=”DSN=AlertingValue” _ “;UID=sa;PWD=sa” cn.Properties(“Prompt”) = adPromptComplete rs.Open “select TagName from AlertingTagValue”,_ cn,adOpenKeyset,adLockOptimistic,adCmdText c. Get and display the current alarm limit value of the monitored parameter to be operated If gTagDb(PublicTag).Value = “LT-2C2101” then FrmAlertingV.Caption = “Inhibitory 1# Chemical Dosing Tank Level” +_ “Online Modification of Alarm Upper and Lower Limits” Upper = gTagDb(“UpperLimit”).Value Lower = gTagDb(“LowerLimit”).Value frmAlertingV.TextBox1.Text = gTagDb(Upper).Value frmAlertingV.TextBox2.Text = gTagDb(Lower).Value Else … … End if d. Modify the alarm upper and lower limits and store them in the AlertingValue database Upper = gTagDb(“UpperLimit”).Value Lower = gTagDb(“LowerLimit”).Value gTagDb(Upper).Value = Val(TextBox3.Text) TextBox1.Text = gTagDb(Upper).Value gTagDb(Lower).Value = Val(TextBox4.Text) TextBox2.Text = gTagDb(Lower).Value Do While Not rs.EOF If rs!TagName = Upper then rs!TagValue = Val(TextBox3.Text) End if If rs!TagName = Lower then Rs!TagName = Val(TextBox4.Text) End if rs.Update rs.MoveNext Loop e. The tags corresponding to the upper and lower limits of alarms for each industrial control parameter are all of type Memory. However, data modified by Memory type tags cannot be permanently stored in the DCS system. Therefore, in order to ensure that the most recently modified values ​​of the alarm upper and lower limits of the industrial control parameters remain valid when the DCS system restarts, the DCS system must retrieve the values ​​of the alarm upper and lower limits of each industrial control parameter from the AlertingValue database again when the DCS system restarts. To implement this function, the program is written as follows: Dim cnDcs As New ADODB.Connection Dim rsDcs As New ADODB.Recordset cnDcs.ConnectionString=”DSN=AlertingValue” _ “;UID=sa;PWD=sa” cnDcs.Properties(“Prompt”)=adPromptComplete rsDcs.Open “select TagName from AlertingTagValue”,_ cn,adOpenKeyset,adLockOptimistic,adCmdText Do While Not rsDcs.EOF gTagDb(rsDcs!TagName).Value= rsDcs!TagValue rsDcs.Update rsDcs.MoveNext Loop cnDcs.Close f. In the Macro function module of the RSView32 project manager, create a macro file named StartUp and write the following code in it: VbaExec AlertingCriticalValue g. In the System\startup module of the RSView32 project manager, set the system startup macro file to StartUp. This allows the AlertingCriticalValue process to execute simultaneously with the DCS system, retrieving alarm limits for industrial control parameters from the AlertingValue database, thus providing reliable data for safe system operation. 3. Conclusion In the offshore platform water treatment DCS system, utilizing the embedded language of RSView32 configuration software—VBA—along with network and database management technologies, online management of alarm limits for industrial control parameters of the platform water treatment DCS system was achieved while the host computer monitoring system was running normally. Without increasing any hardware or software costs, this enhanced the system's data management capabilities, improved its scalability and reliability, eliminated potential safety hazards caused by process improvements and equipment upgrades in offshore oil production, provided reliable assurance for the safe operation of platform oil production, and offered valuable lessons for the construction of enterprise computer control systems. References: 1. Rockwell Automation. RSView32 User' Guides. 2. [US] E. Winemiller, J. Roff, B. Heyman, R. Groom. Visual Basic 6.0 Database Development. Tsinghua University Press. 1999.9. 3. [US] David Jung, Pierre Boutquin, John D. Conley III. Visual Basic 6 Developer's Reference Manual. Machinery Industry Press. 2000.1. 4. [US] Michael Otey, Paul Conte. SQL Server 2000 Development Guide. Tsinghua University Press. 2002.1. 5. Liu Changyu, Zhang Zhaoyun, Liu Wei. Real-time Information Exchange between RSView32 and C++ Builder Application Software. Computer Engineering and Applications. 2001.7 103-106. 6. Chen Zengqiang, Zhao Tianhang, Liu Zhongxin, et al. Design of Industrial Boiler Monitoring System Based on Windows NT Environment. Computer Engineering and Applications. 2000.8 163-165. 7. Zou Tong. Programming Techniques of WinCC Configuration Software. Chemical Automation and Instrumentation. 2001. 28(2): 63-64. 8. Wang Suzhen et al. Application of Rockwell RSView32 in Monitoring System of Water Injection Process on Offshore Platform. Electrical Automation. 2002. Vol. 24. No. 6. 9. Shao Shan et al. Development and Application of Automated Alarm Systems. Automation of Electric Power Systems. 2001. 1. Vol. 25. No. 2.