Differences between DSC and PLC control systems
DSC and PLC control systems are very commonly used systems in the industrial control industry, so what are the differences between these two control systems? Which is better? PTJ will introduce to you.
In fact, the design principles of DCS and PLC are quite different. PLC was developed by mimicking the original relay control principle. In the 1970s, PLC only had switch logic control. The first application was the automobile manufacturing industry. It stores instructions for performing logical operations, sequence control, timing, counting, and operations; and through digital input and output operations, it controls various machinery or production processes. The control program compiled by the user expresses the technological requirements of the production process and is stored in the user program memory of the PLC in advance. When running, it is executed one by one according to the contents of the stored program to complete the operations required by the technological process.
There is a program counter in the CPU of the PLC that indicates the storage address of the program step. During the program running, the counter is automatically incremented by 1 every time the program is executed. The program is executed from the initial step (step number is zero) to the final step (usually END) Instruction), and then return to the initial step of cyclic operation. The time required for the PLC to complete a cycle operation is called a scan cycle. For different types of PLC, the cyclic scanning period is between 1 microsecond to tens of microseconds. The cyclic operation of the program counter is something that DCS does not have.
When users choose the DCS and PLC control system, they can choose according to their own situation and requirements, so that they can be handy when running in the future.