Style guide

Programming style guidelines for the MotoLogix code examples.

The goal of these guidelines is to make the code more uniform and improve its readability.

Programming conventions

1. All programming in Structured Text (ST).
2. Variable names starts with a prefix .
3. Function parameters do not use a prefix.
4. Constants are written in UPPERCASE, use the underscore (_) as separator and do not use a prefix.
5. Focus on platform compatibility by favouring plain/universal code over platform specific functions.
6. Wrap program code lines at max 80 characters.
7. Tabs as spaces.
8. Tab width: 2 characters.
9. No trailing whitespace.

Coding reference

One shot signals

// -----------------------------------------------------------------------------
// declaration
// -----------------------------------------------------------------------------
bMyInput: BOOL; // input for testing the one shot logic
aOneShots: ARRAY [0..9] OF BOOL; // bits for creating one shot signals
bOsrMyInput: BOOL; // rising edge for MyInput
bOsfMyInput: BOOL; // falling edge for MyInput


// -----------------------------------------------------------------------------
// logic
// -----------------------------------------------------------------------------
// rising edge
bOsrMyInput := bMyInput AND NOT aOneShots[0];
aOneShots[0] := bMyInput;

// falling edge
bOsfMyInput := NOT bMyInput AND NOT aOneShots[1];
aOneShots[1] := NOT bMyInput;

Naming conventions

Variables

Below table lists the prefix for each data type.