ABB AC 800M, Руководство по стилю объекта библиотеки

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Function Block Example Section 4 Engineering Interface
52 3BSE042835-600
ManMode is better than MANMODE. The POU editors allow use of upper and
lower case letters for declaration of parameter names, and that the user refers to the
name in any form, as long as the letters are the same (for example entering
ManMode is the same as entering MANMODE).
A short name is more space efficient to use than a long name and easier to read. This
assumes, of course, that the user knows what the name means. Standardized short
names or acronyms are most helpful in this respect, for example Pv = Process Value,
and T = time. It should also be kept in mind that a long name not necessarily
provides more - or enough - information. Hence, a shorter name together with a
good description proves often to be the best alternative.
In addition, in the editor, it is often possible to show the parameter description
adjacent to the parameter name for more clarity. Seldom used or unusual parameter
names may require longer names to be understandable (for example SourceSuffix),
compared to traditionally used names (for example Min).
With the exception of InteractionPar (see further Section 5, Operator Interface ), the
length of parameter names in functions and Function Block types shall not exceed
eight characters. When this is not possible, up to twelve characters are allowed.
These restrictions apply equally to graphically connected parameters in control
module types. Other parameter names in control module types shall be as short as
possible, and easy to understand. Note, however, that for custom designed object
types, the user may assign longer names to parameters, up to the system limit of 32
characters.
Avoid structured data types in Function Block types because these are not suitable
in Functions Block Diagrams, since it is not possible to connect the components to
other function blocks. The parameters in the connection list should be divided into a
number of groups. The grouping of the parameters should be done in an object
oriented way. This means for example that Min, Max and Unit of a signal should be
grouped together with the signal itself.
Function Block Example
The declared parameter direction will affect the graphical layout of the function
block. Each parameter will appear in the sequence it has been declared, whereas
parameters of IN direction will appear on the left side, and OUT parameters on the
right side in the FBD language.