The concepts of soft points and hard points?
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What do soft points and hard points refer to, respectively?
The so-called hard points refer to the actual IO points, that is, the physical points, such as AI, AO, DI, DO, PI, etc. A soft point generally refers to a variable point established in a control system or host computer configuration software—a point that does not exist physically.
Look around; it seems there’s a discussion on the forum about this. A soft point is an internal point, and its definition derives from a hard point. Different from hard points, these are naturally soft, haha. Remember the hard points – everything else are soft points. Hard points refer to those on the card units that are supported by hardware (such as DI, DO, AI, AO cards, etc.)
Is that soft spot reflected in the flowchart? Can it be seen?
Soft points are generally not visible in flowcharts; for example, in the case of steam flow, what is collected as hard points are the raw flow values. What is displayed on the DCS screen should be the values after temperature and pressure compensation using soft points. If DCS engineers follow a consistent naming convention for soft points and hard points during configuration, it should be possible to distinguish between them based on their tag numbers on the screen. Unless there are issues such as line failures, it is generally not necessary to know whether it is a hard point or a soft point.
5# Graham, thank you. But is the temperature and pressure compensation calculated through the DCS, or is it provided by the instrument itself – not handled directly by the instrument?
We usually treat it as something tough
Simply put, a hard point is one that is connected by a wired connection, while a soft point is one defined within the internal program
I’m not sure whether the global variables we often talk about include soft points and hard points as well
For 6# Keninghu, there are methods for temperature and pressure compensation of steam flow. One approach is as you mentioned: using a secondary meter to which the temperature, pressure, and flow signals are fed; this meter then performs calculations to produce a compensated flow value, which is sent to the DCS. Another method involves feeding the temperature, pressure, and flow signals directly into the DCS, where the DCS itself calculates the flow value for display. Personally, I don’t think one method is necessarily better than the other; it simply depends on the specific requirements
Simply put. Start a pump. . . Press the button to open the DCS screen. . . . Soft point: On button of the on-site control panel; Hard point