Glossary
What is Type conversion?
Explicit functions that move a value between types, such as INT_TO_REAL, REAL_TO_INT, TRUNC and TIME_TO_DINT.
The standard is strict: in most cases it does not convert implicitly and you must write the conversion yourself. It feels tedious but it prevents silent errors.
Mind the difference: TRUNC(3.9) is 3 because it cuts the fraction, while REAL_TO_INT(3.9) is 4 because it rounds. Picking the wrong one costs a whole step in position calculations.
Related terms
- Integer division
- Dividing two integers in ST gives an integer and the fraction is dropped, which is a common cause of an unexpected zero.
- Analogue scaling
- Turning the raw count from an input card into an engineering unit an operator understands: metres, bar or degrees.
- Data type
- The classification that fixes a variable size, value range and permitted operations: BOOL, INT, DINT, REAL, TIME and the rest.