BS EN 61131-1:2003 – Programmable controllers — Part 1: General information

3 Terms and definitions For the purposes of this document, the following terms and definitions apply.
3.1 application programme or user programme logical assembly of all the programming language elements and constructs necessary for the intended signal processing required for the control of a machine or process by a PLC-system 3.2 automated system control system beyond the scope of IEC 61 1 31 , in which PLC-systems are incorporated by or for the user, but which also contains other components including their application programmes
3.3 field device catalogued part to provide input and/or output interfaces or to provide data pre- processing/post-processing to the programmable controller system. A remote field device may operate autonomously from the programmable controller system. It can be connected to the programmable controller using a field bus
3.4 ladder diagram or relay ladder diagram one or more networks of contacts, coils, graphically represented functions, function blocks, data elements, labels, and connective elements, delimited on the left and (optionally) on the right by power rails
3.5 programmable (logic) controller (PLC) digitally operating electronic system, designed for use in an industrial environment, which uses a programmable memory for the internal storage of user-oriented instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic, to control, through digital or analogue inputs and outputs, various types of machines or processes. Both the PLC and its associated peripherals are designed so that they can be easily integrated into an industrial control system and easily used in all their intended functions NOTE The abbreviation PLC is used in this standard to stand for programmable controllers, as is the common practice in the automation industry. The use of PC as an abbreviation for programmable controllers leads to confusion with personal computers.
3.6 programmable controller system or PLC-system user-built configuration, consisting of a programmable controller and associated peripherals, that is necessary for the intended automated system. It consists of units interconnected by cables or plug-in connections for permanent installation and by cables or other means for portable and transportable peripherals
3.7 programming and debugging tool (PADT) catalogued peripheral to assist in programming, testing, commissioning and troubleshooting the PLC-system application, programme documentation and storage and possibly to be used as HMIs. PADTs are said to be pluggable when they may be plugged or unplugged at any time into their associated interface, without any risk to the operators and the application. In all other cases, PADTs are said to be fixed
BS EN 61131-1:2003 – Programmable controllers — Part 1: General information