Configuration software is increasingly widely used in industrial control. Based on its own process database, configuration software connects to various hardware devices and, through a dynamic human-machine interface, displays the collected and processed data to the user or transmits it to other applications. Its structure is shown in the figure. The emergence of configuration software, by providing various commonly used components and related device drivers in advance, has greatly reduced the difficulty of designing monitoring systems and shortened the development time. Furthermore, its ability to freely connect to various devices provides a platform where users can design cost-effective projects according to their needs. For hardware devices, especially programmable PLCs, which have certain control functions, configuration software that can connect to PLCs can also execute certain control functions through scripts. So, is control handled by the host computer configuration software or the slave computer PLC? Here is a simple comparison: Slave Computer Control The slave computer can execute some related control actions. Its advantages are high speed, high reliability, and stability. Its disadvantage is that it is limited by its own limitations; it cannot execute some special complex controls, or control functions related to other special equipment or involving relational databases. Upper Computer Control The configuration software on the upper computer can also execute certain control actions. Its advantages include easier script writing and the ability to easily execute control actions involving multiple devices, relational databases, or other data, fully leveraging the system's strengths. Disadvantages include potential communication bottlenecks between the upper and lower computers, and the fact that the configuration software often runs on industrial control computers with different operating systems, resulting in stability differences compared to PLCs. In practical engineering, control distribution should be tailored to specific needs. The following are some typical examples suitable for lower computer control scenarios : For applications with high real-time requirements, or where communication between the upper and lower computers is slow or easily interfered with, it is recommended to place critical controls on the lower computer. For example, in typical water conservancy projects, such as water quality monitoring, the substations of the monitoring system and the central station running the configuration software may be far apart, and communication may use methods such as data radio, dial-up, GSM, or GPRS. In this scenario, due to the long communication distance, there may be some delay. Therefore, the control functions are mostly handled by the lower-level computer, while the upper-level computer is mainly responsible for data acquisition, storage, and display, and may also include some configuration functions for the lower-level computer. Suitable Scenarios for Upper-Level Computer Control For control functions related to relational databases or multiple devices, relying solely on the lower-level computer for control may be very cumbersome or difficult to implement. In such cases, it is recommended that the upper-level computer handle the control. For example, station lighting control requires obtaining train operation signals and other data to determine whether to turn on the lights. Train operation signals are generally stored in a database or obtained from the guidance system. In this case, if the control is almost entirely implemented by the upper-level computer, it would be problematic. More often, the settings are based on the characteristics of the control function itself. The lower-level computer and the upper-level computer can each execute relevant control functions as needed. Controls with high real-time requirements can be placed on the lower-level computer, while complex controls involving other data can be placed on the upper-level computer. Together, they form a complete control system. Reasonable allocation not only reduces workload but also improves the robustness of the project.