This article is about Historization and Trending of DCS System as per international codes and ARAMCO engineering standards SAES-Z-001 and others.
Making the Most of DCS Historization and Trending
DCS, or distributed control systems, play a vital role in providing efficient process control for a range of industries. As such, it is essential to ensure that the DCS is operating at peak performance and is properly configured to collect and store data. Historization and trending are two key features of DCSs that allow for efficient data collection and visual representation of performance. This article will explore the importance of DCS historization and trending, as well as how to make the most of these features.
What is DCS Historization and Trending?
DCS historization is the process of capturing and storing data from a DCS system over a period of time. This data can then be used to monitor system performance, identify trends, and detect anomalies in the system. Trending is the process of visualizing data collected from the DCS over a period of time. This allows for easy analysis of data and quick identification of potential issues.
Why is DCS Historization and Trending Important?
DCS historization and trending allow for quick and accurate visual analysis of data collected from the system. This allows operators to quickly identify issues and take corrective action, as well as to track performance over time. Additionally, historization and trending can be used to detect anomalies in the system and prevent potential problems before they become serious.
What Parameters Should Be Historized?
DCS systems should be configured to historize a variety of parameters in order to ensure accurate data collection. At a minimum, the following parameters should be historized:
• Process value (PV) for all analog inputs used for monitoring only
• Process value (PV) for all discrete inputs
• For PID controllers, all PV, SP, and MV or output values
• All calculated variables such as compensated flows or flow totalizers
• Output value for all analog output only tags (i.e. manual loaders) and discrete outputs to the field
How to Set Up Historization and Trending
DCS historization and trending can be easily configured within the system. The collection rates, longevity, and scope for historical data should be specified on a per project basis. The minimum allowable collection rates and longevity are typically listed in the system documentation. Additionally, DCS real-time trends should be configured for all analog input tags and control loops, with a data update rate of nominally two seconds.
DCS historical trends should also be configured for all analog input tags and control loops. For control loops, MV, PV, and SP should be recorded on the same trend. Furthermore, the system should be configured to enable an operator to call-up a real-time trend for any process tag or calculated variable in his process area from any workstation within his operator console.
Conclusion
DCS historization and trending are important features of DCS systems that allow for efficient data collection and visual representation of performance. By properly configuring the system to historize and trend the right parameters, operators can easily monitor system performance, identify trends, and detect anomalies. This helps prevent potential problems before they become serious and ensures that the DCS system is operating at peak performance.

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