1. Storage capacity
Storage capacity refers to the user program memory capacity. User program memory capacity, you can develop complex programs. Generally, small PLC user memory capacity for thousands of words, and mainframe user memory capacity of up to tens of thousands of words.
2. I/O pointsInput/output (I/O) points is acceptable to the PLC the sum of the input signal and the output signal, an important indicator of performance is a measure of PLC. More I/O points, external input devices and output devices, the more controlling greater scale.
3. Scan speed
Scan speed refers to the speed of PLC user programs, an important indicator of performance is a measure of PLC. General scan 1K the Word user time required by the program to measure speed, usually in units of ms/K. PLC user‘s manual General given the implementation of the directive in time, you can perform the same operation using PLC time, measured and slow scanning speed.
4. Function and number of instruction
Instruction function of intensity, quantity is also important index to measure performance of PLC. Number of programmed instruction more powerful, more PLC and control more powerful, more simple and convenient user programming is, the more complex control tasks.
5. Number and type of internal components
At the time of preparation of the PLC program, requires the use of a large number of internal components to store variables, intermediate results, data, time count, module settings and a variety of flags and other information. The types and quantities of these components more PLC‘s ability to store and handle all kinds of information is.
6. Special function unit
Special types of functional units and functional strength is an important indicator for measuring PLC products. In recent years various PLC manufacturers attach great importance to development of special function unit, special function unit types growing more powerful, PLC control functions has expanded.
7. Scalability
Extended capabilities including I/O point number extension of the PLC, storage capacity extension, networking extension, expansion of the various functional modules, and so on. When choosing a PLC, often need to consider scalability PLC.
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