Types of Siemens 400 PLC
Thread Content
I’d like to discuss the differences between the standard, safety, and fault-tolerant types of CPUs in 400PLC, as well as the situations in which each type is suitable
Share my humble opinion. The standard version is somewhat underwhelming; if a 300 PLC can meet your requirements, there’s no need to choose the 400 standard version. It is essentially just an extension of the 300 model in terms of the number of IO points and program size. The safety type is used in applications where the system has SIL requirements, such as ESD/FGS. Fault-tolerant design improves availability compared to a single CPU, preventing shutdowns due to CPU failures. For example, a one-hour shutdown of wastewater treatment in a factory won’t cause the entire plant to stop operating, so there’s no need for fault tolerance ； But it’s a problem if the desalinated water is unavailable for such a long time.
Can it be understood in this way: a safety-type system is one that integrates DCS and SIS?