© Tony Simmons 2010
Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.
Glossary of Automation & Control Engineering Terms
Ladder Lgic
This term dates to the time when programmable logic controller software was developed to replace hardwired relay circuits. The programming style simulated the way relay circuit diagrams were drawn and gave rise to the expression 'ladder logic'.
Ladder diagram (LD) is one of the IEC61131-3 standard languages. A LD program enables the programmable controller to test and modify data by means of standardised graphic symbols. These symbols are laid out in networks in a manner similar to a "rung" of a relay ladder logic diagram. LD networks are bounded on the left and right by power rails.
LEL
Lower Explosive Limit
Life Cycle
All the activities associated with the stages of a project from the initial preparation of the requirements specification to the final disposal of a computer-based system.
Each stage of the life cycle model is defined in terms of the outputs produced during the stage, not by the activities occurring during the stage. In this way tangible progress can be measured.
LIMS
LIMS - Laboratory Information Management System.
Loop Testing
Checking the installed combination of elements characterising each type of Input/Output loop.[GAMP]
Cold Loop testing refers to the check out of field loops from the field termination cabinet where multi-core field cables interface to the PCS I/O cards.
Hot Loop testing refers to the checking of the entire loop from the operator keyboard which exercises the I/O database and graphic screens as well as cabling and field devices. To separate software from hardware problems it is essential that cold loop testing is done first.
