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This post was last edited by Huahua Jianghu on 2020-3-19 at 16:14. According to IEC61508, safety functions aimed at reducing risks are classified into instrument functions, non-instrument functions, and other functions. In terms of functional safety, instrument safety functions are divided into BPCS and PES; those with a safety integrity failure probability greater than 0.1 belong to DCS, while those with a probability less than 0.1 are classified as PES. IEC 61508 clearly defines instrument functions; the key point is that any product that utilizes electronics, electricity, or programming can be considered an instrument function, which in IEC 61511 is referred to as SIS. So things like ESD, ITCC, BMS, and so on are related to electronics, electrical systems, and programming structures; they fall under PES or SIS. It has absolutely nothing to do with whether a manufacturer can do it, how they do it, whether integration is involved, or things like scanning time or algorithms. That’s why some ITCC, ESD, and BMS manufacturers now claim that their products have passed SIS certification – and this is the proof. The SIS system is divided into safety control functions and protection functions, with the safety control function operating in a continuous mode. Therefore, all systems can be classified as BPCS or PES (SIS). Reallocation based on integration, scanning time, or algorithm is nothing more than changing the appearance of baozi by tweaking its design. As for why subsystems such as ESD, ITCC, BMS, and FGS are still in use instead of being integrated into BPCS or PES (SIS), it is because these facilities are quite important and special, so they are kept separate for easier management from a production perspective. Additionally, traditional practices continue to be followed, and there are also commercial reasons for this. Technically speaking, they should actually be merged.