This International Standard specifies requirements and makes recommendations for the design, integration and validation of safety-related control systems (SCS) for machines. It is applicable to control systems used, either singly or in combination, to carry out safety functions on machines that are not portable by hand while working, including a group of machines working together in a co-ordinated manner. This standard is machinery sector specific standard within the framework of the IEC 61508 series. The design of complex programmable electronic subsystems or subsystem elements is not in the scope of this standard. This is in the scope of IEC 61508 or standards linked to it, see Figure 1. The main body of this sector standard specifies general requirements for the design, and verification of a safety-related control system intended to be used in high/continuous demand mode. Specific requirements for design, and verification of a safety-related control system intended to be used in low demand mode are given in normative Annex D. NOTE 1 It s recognized that a subsystem can be shared by high and low demand functions. This standard: is concerned only with functional safety requirements intended to reduce the risk of injury or damage to the health of persons in the immediate vicinity of the machine and those directly involved in the use of the machine; is restricted to risks arising directly from the hazards of the machine itself or from a group of machines working together in a co-ordinated manner; NOTE 2 Requirements to mitigate risks arising from other hazards are provided in relevant sector standards. For example, where a machine(s) is part of a process activity, additional information is available in IEC 61511. This document does not cover electrical hazards arising from the electrical control equipment itself (e.g. electric shock see IEC 60204 1); other safety requirements necessary at the machine level such as safeguarding; specific measures for security aspects see IEC TR 63074. This document is not intended to limit or inhibit technological advancement. Figure 1 shows the relationship of this standard to other relevant standards.