(1) integrity principle the PLC system must be complete. Everything that should be done must be done. If the item is lost and then added during installation or use, it will not only bring a lot of trouble, but also may delay the construction period.
(2) principle of reliability PLC system must be reliable. Can be considered from four aspects: one is the PLC itself product quality; Second, the technical service of the supplier; Third, whether the work requirements under important or special occasions can be met; Fourth, whether to redundant configuration.
(3) the principle of development of PLC working life is long, but the technical life is not long. PLC is often not used out of order, but has not been used out of order, as a result of backward, had to be eliminated. Therefore, PLC system configuration should adhere to the principle of development. There are two main points: the system configuration to leave room for development; When selecting PLC, the new model should be used as far as possible.
(4) the principle of inheritance system configuration should also take into account the historical use of PLC. If the newly configured system has an inheritance relationship with the existing system, the programmer and some programming software can be reused. The valuable experience accumulated can also be used in the field; Some modules are even portable. This is of great benefit to shortening programming time and correctly using PLC.
(5) the principle of economy whether economically, should also be used as whether the adoption of PLC, what kind of PLC to use the important evaluation criteria. Obviously, after the system configuration, it should be evaluated by the benefit.