The DCS (Distributed Control System) communication network consists of multiple nodes, typically categorized into two main types. The first type is the controller node, directly connected to the production process via I/O modules. These controllers are responsible for data acquisition and loop control, and they can be combined into a single unit. The second type includes human-machine interface (HMI) nodes, which interact with operators and collect data from the controllers. These HMIs include operation stations, engineer workstations, historical trend stations, and dynamic data servers. Operation stations are the primary tools used by factory operators to monitor and control the system. They receive data from the controllers and send operator inputs back, making the communication two-way. Engineer workstations are used to configure the system before it goes live, loading algorithms and parameters into the controllers. This configuration process differs from traditional programming and is more about setting up the system according to specific needs. Controllers also contain various control algorithms, such as PID, mathematical operations, trigonometric functions, and advanced techniques like the Smith predictor. If the built-in mapping features in the operation station aren't sufficient, engineers can create custom dynamic flowcharts and load them into the HMI. A reverse engineering station plays a key role in upgrading systems without altering existing configurations. It can also help diagnose issues by reading the controller's setup. Another important component is the dynamic data server, which acts as a bridge between the DCS and the MIS (Management Information System). It ensures one-way data flow from the DCS to higher-level systems and handles large volumes of data. Historical trend stations function similarly to dynamic data servers but can either operate independently or be integrated into a single node. Network congestion is common during initial system deployment due to incomplete configurations, but this usually stabilizes over time. However, when the dynamic data server connects to the network, frequent congestion and HMI crashes may occur, often linked to misconfigured data points. When connecting to the DCS network, each node uses a network interface to communicate. Data is broadcast across the network, and only the nodes that need the information process it. Bus networks are logically ring-shaped, while star networks are only suitable for small systems with fewer than 100 I/O points. Crashes in operation stations have been a long-standing issue since the 1970s. Early systems suffered from software mismatches between the operating system, monitoring tools, and controller drivers. Some DCS systems used third-party software, leading to compatibility problems and more frequent crashes. Dynamic data servers were not part of early systems but have become essential in recent years. As the system runs longer, maintenance staff changes, and configurations evolve, some settings may no longer align with actual I/O points. When the dynamic data server is activated, it reads all data points, many of which may be invalid, causing network congestion and crashes. A reverse engineering station can help identify and remove these invalid points to restore stability. It’s crucial to ensure all software versions are consistent when accessing the dynamic data server, as mismatched versions can disrupt data transmission. Another solution to reduce network traffic is the exception reporting method. This technique transmits data only when a point changes, significantly reducing unnecessary traffic. To prevent missing updates, even static data is reported periodically, and adjusting the reporting interval can further optimize performance. Modern operation stations typically run on the NT operating system, paired with widely-used monitoring software like FIX or INTOUCH. Due to their popularity, these systems have fewer bugs and better open performance, reducing crashes and making maintenance more cost-effective. This advancement marks a significant improvement in DCS technology, offering greater flexibility and reliability.
The shortpass filter means that in a specific wavelength range, the short-wave is transmitted, and the long-wave is cut off, which plays the role of isolating the long-wave.
These filters can be used in a variety of cut-off wavelengths and are very suitable for fluorescence applications, spectral analysis applications, and applications that combine long-pass filters to achieve customized effective band-pass filters.
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