Fourth, programming devices Plc programming can purchase three ways :   Using hand-held programming device programming in general, it can provide businesses phrases programming language table. This approach inefficient, but the capacity of small systems, the products more suitable for small consumption, and small size, ease of debugging scene, but also lower costs. Using graphical programming device programming, the programming device used Trapezoid Chart programming for visual and general electrical personnel shortly be applied easily, but the programming device prices higher. Using IBM personal computers and software packages using Plc programming, this approach is the most efficient way, but most of the company's Plc development software packages expensive, and that means not at the scene debugging.   Therefore, the system should be based on the size and level of difficulty, the length of the development cycle and reasonable funding of the purchase Plc products.

Fifth, And large companies to choose their quality guaranteed products, and good technical support, after sales services are generally better, but also help expand your product and software upgrades.

For small systems, such as 80 points within the system. Generally do not need expansion; When a larger system, we must expand. Different companies products to the total points system and the expansion of the number of modules have limitations when expansion can not meet the requirements, can network structure; At the same time, some manufacturers of inpidual products do not support the expansion module directives, in software development, we must pay attention to. When using such simulation module temperature, some of the manufacturers, see related technical manuals. Many types of companies expansion modules, such as single-input modules, single output modules, input output modules, temperature modules, high-speed input module. This modular design Plc product development provided for the convenience of users.

When using a Plc network design, its much more difficult to control than single Plc. First you should choose their own more familiar type, its basic instructions and a more in-depth understanding of the functional commands, and the speed and direction of the implementation of storage capacity users should also be careful about the procedure. Otherwise, you can not adapt to the real-time requirements, resulting in the collapse of the system. In addition to communications interfaces, communication protocols, data transmission speed should also be considered. Finally, we must seek to Plc businessmen network design and software technical support and detailed technical information for the selection of several workstations in your system size.

In the preparation of the software, should first become familiar with the use of Plc software products specification, the question skilled later programming. If using graphical programming device or software package programming may direct programming, if using hand-held programming device programming, should be painted Trapezoid Chart before programming, so can less mistakes speed was fast. After the first air conditioning programming procedures to be normal functioning of all, again in equipment debugging.

Ⅰ.system analysis and synthesis

1．Analysis  

（1）In the speed and current dual closed-loop speed control system, in order to change the motor speed, what parameters should be regulating? Change speed regulator Kn magnification work? Power electronic converter to change the magnification factor Ks work? Change the speed of the feedback coefficient of work? To change the motor's stall current system should adjust the parameters of what?

A: To change the motor speed, change speed regulator Kn magnification and power electronic converters will not work magnification factor Ks, stable when n = Un = Un *, so the only change in the value of a given coefficient of Un * and feedback before. To change the motor's stall current, only need to change the same value given Uim * and feedback coefficient, because the stability, Uim * = Idm, can be drawn from the type