Languages used in TIA Portal
This section covers five of the languages available in TIA Portal and demonstrates their usage against the control scenario.
Ladder logic
LAD is the most popular language in the PLC control space. It's likely that programmers of PLCs have never seen or used LAD. Although it's still extremely popular, other languages such as SCL are also becoming very popular.
Overview
Ladder gets its name from the way that the logic flows from the left of a network to the right of a network. When multiple networks are placed in series, a ladder is formed.
Ladder, like other languages that are programmed in networks, is processed as follows:
- Networks
- Top to bottom
- Logic inside networks
- Left to right.
- Top to bottom.
- Conditions that come to a common point (the closing of a branch) will evaluate all conditions left of the common point before proceeding.
- Outputs/instructions that are on open branches will be processed top to bottom from the point...
