The scheme is a drawing or the image describing the main idea of any device or a construction. It can be carried out without observance of scale and symbols. In design documentation describes components of a product, connection between them.
Block diagram
The block diagram gives a general idea about the principle of operation of the device. On it the set of links of an object, communication between them is represented. Each link is a part of an object and is responsible for some elementary function.
Principles of creation of the block diagram
Links on the scheme represent in the form of rectangles or conditional graphic symbols which connect lines of interrelation. These lines should be designated by arrows for the indication of the direction of the course of processes between links. Each link of a product on the scheme has to have the name or designation.
The name can be in the form of a symbol and describe element type. In the block diagram use of additional schedules, charts and tables is allowed and also it is possible to specify parameters and characteristics. The block diagram has to give an idea of interaction of links of a product.
Principles of creation of the function chart
The function chart lets know what occurs in separate nodes of the device, explains the principle of its work. Functional parts of the device and communication between them designate with a type of special graphic symbols. Separate functional parts are allowed to be represented in the form of rectangles. If the device or a link is represented in the form of a rectangle, then its type and the document on the basis of which this device is used has to be specified. The symbol has to be appropriated to each element of the function chart. It is recommended to specify technical characteristics of each functional part of the device. For each group of functional elements the designation appropriated to it on the scheme or its name has to be specified. On the function chart the image of additional schedules, charts, the tables determining the sequence of the processes which are taking place in the device by time and also the indication of characteristics of separate elements and points (tension, current, impulses, etc.) is allowed.
Difference of the block diagram from functional
Thus, the distinction of structural and functional schemes is that the block diagram depicts an overall picture of the device and indicates location of functional elements and links, and functional describes the provision of elements in knots, interaction between scheme elements more precisely.