This Part of IEC 61131 applies to programmable controllers (PLC) and their associated peri-pherals such as programming and debugging tools (PADTs), human-machine interfaces (HMIs), etc., which have as their intended use the control and command of machines and industrial processes.PLCs and their associated peripherals are intended to be used in an industrial environmentand may be provided as open or enclosed equipment. If a PLC or its associated peripheralsare intended for use in other environments, then the specific requirements, standards andinstallation practices for those other environments must be additionally applied to the PLC and its associated peripherals.The functionality of a programmable controller can be performed as well on a specifichardware and software platform as on a general-purpose computer or a personal computerwith industrial environment features. This standard applies to any products performing thefunction of PLCs and/or their associated peripherals. This standard does not deal with thefunctional safety or other aspects of the overall automated system. PLCs, their applicationprogramme and their associated peripherals are considered as components of a control system.Since PLCs are component devices, safety considerations for the overall automated systemincluding installation and application are beyond the scope of this Part. However, PLC safetyas related to electric shock and fire hazards, electrical interference immunity and errordetecting of the PLC-system operation (such as the use of parity checking, self-testingdiagnostics, etc.), are addressed. Refer to IEC 60364 or applicable national/local regulationsfor electrical installation and guidelines.This Part of IEC 61131 gives the definitions of terms used in this standard. It identifies theprincipal functional characteristics of programmable controller systems.