Several conventions are used to simplify the use of the REXYGEN control system. All used variable types were defined in the preceding chapter. The term variable refers to function block inputs, outputs and parameters in this chapter. The majority of the blocks uses only the following three types:
- Bool – for two-state logic variables, e.g. on/off, yes/no or true/false. The logic one (yes, true, on, 1) is referred to as on in this manual. Similarly the logic zero (no, false, off, 0) is represented by off. This holds also for REXYGEN Studio. Other tools and 3rd party software may display these values as 1 for on and 0 for off. The names of logic variables consist of uppercase letters, e.g. RUN, YCN, R1, UP, etc.
- Long (I32) – for integer values, e.g. set of parameters ID, length of trend buffer, type of generated signal, error code, counter output, etc. The names of integer variables use usually lowercase letters and the initial character (always lowercase) is in most cases , e.g. ips, l, isig, iE, etc. But several exceptions to this rule exist, e.g. cnt in the COUNT block, btype, ptype1, pfac and afac in the TRND block, etc.
- Double (F64) – for floating point values (real numbers), e.g. gain, saturation limits, results of the majority of math functions, PID controller parameters, time interval lengths in seconds, etc. The names of floating point variables use only lowercase letters, e.g. hilim, y, ti, tt.
The function block names in the REXYGEN system use uppercase letters, numbers and the ’_’ (underscore) character. It is recommended to append a lowercase user-defined string to the standard block name when creating user instances of function blocks.
It is explicitly not recommended to use diacritic and special characters like spaces, CR (end of line), punctuation, operators, etc. in the user-defined names. The use of such characters limits the transferability to various platforms and it can lead to incomprehension. The names are checked by the REXYGEN Compiler compiler which generates warnings if inappropriate characters are found.
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