PREMISE
The set of devices that allow humans to communicate with machines is called "human-machine interface".
The interface, in addition to including the commands and signals relating to the normal use of the machine, includes the set of warnings/signals for reporting emergencies or faults as well as the commands for managing these particular conditions.
The controls must always be easily accessible and clear so as not to mislead the machine operator and must be easily understandable even by manufacturers or users of different nationalities.
The characteristics of the human-machine interface are covered both by Directive 2006/42/EC and by many technical standards specific to the subject.
MACHINERY DIRECTIVE 2006/42/EC
Annex I - RESS 1.1.6 Ergonomics
Under the intended conditions of use, the discomfort, fatigue and mental and physical tension (stress) of the operator must be reduced to the minimum possible, taking into account the following ergonomic principles:
- take into account the variability of the operator's physical size, strength and endurance,
- provide the necessary space for the movements of the operator's body parts,
- avoid a work pace conditioned by the machine,
- avoid a control that requires prolonged concentration,
- adapt the human/machine interface to the predictable characteristics of the operator.
The requirements in point 1.1.6 refer to ergonomics. The discipline of ergonomics can be defined as follows:
"Ergonomics (or the study of human factors) is the scientific discipline that studies the interaction between the elements of a system (human and otherwise) and the profession that applies the theory, principles, data and methods by which they are designed with the aim of optimizing user satisfaction and the performance of the system itself."
The ergonomic aspects referred to in point 1.1.6 can be divided into two groups. The first group includes the ergonomic factors to be considered during the design of the machine. The indents of point 1.1.6 list five factors, but it should be noted that the list is not exhaustive, its only purpose being to draw the attention of manufacturers to certain important aspects of ergonomic principles.
The second group, listed in the first sentence of point 1.1.6, includes the possible negative effects of these factors. Good design has the effect of reducing the negative effects of these factors on people, while poor design can cause discomfort, fatigue or physical or psychological stress, which in turn lead to possible musculoskeletal disorders, for example. They also increase the likelihood of accidents.
Annex I - RESS 1.7.1.1 Information and information devices
The information needed to drive a car must be provided in a clear and easily understandable manner.
understandable. They should not be in such quantity as to overlap in the operator's mind.
Display units or any other means of interactive communication between operator and machine must be easy to understand and use.
The requirement in point 1.7.1.1 applies to all information on the machine that is necessary to assist operators in giving commands to the machine. In particular, it applies to indicators and information devices.
Specifications for the design of information, information devices, indicators and display systems are given in the EN 894 series and EN 61310 series standards.
Annex I - RESS 1.7.1.2 Alarm devices
Where the safety and health of persons may be endangered by a failure of machinery operating unattended, the machinery must be equipped to emit an appropriate audible or luminous warning signal.
If the machine is equipped with warning devices, they must be unambiguously understood and easily perceived. Appropriate measures must be taken to enable the operator to check the continued effectiveness of these warning devices.
The provisions of the specific Community directives concerning colours and safety signals must be applied.
Section 1.7.1.2 deals with risks to persons due to failures of machinery or parts of machinery designed to operate without permanent operator supervision. Warning devices must be such as to inform operators or other exposed persons of dangerous failures, in order to enable them to take the necessary action to protect the persons at risk. Where appropriate, warning devices may be fitted to the machinery itself or activated remotely.
EN 61310-1 provides specifications for visual and acoustic signals.
References to the human-machine interface are also part of further RESS in Annex I such as
for example those relating to Control Devices.
REGULATORY REFERENCES
EN 60447, Human-machine interface: operating principles
EN 60073, Coding of indicating devices and actuators, with colours and additional means
EN 61310-1, Safety of machinery: Requirements for visual, acoustic and tactile signals
CEI 64-8, Standards for electrical user systems
EN 60204-1, Safety of machinery: Electrical equipment of machines
EN 60947-5-1, Low-voltage switchgear and controlgear. Part 5: Control circuit devices and switching elements
EN 61439-1 (CEI 17-13/1), Low-voltage switchgear and controlgear assemblies
(BT tables) Part 1: General rules
PLACEMENT AND ASSEMBLY
As far as possible, the control devices mounted on the machine must be:
- easily accessible for service and maintenance;
- mounted in such a way as to minimize the possibility of damage due to activities such as materials handling.
Actuators of manually operated control devices shall be selected and installed so that:
- they are located at a height of not less than 0.6 m above the service surface and are easily reachable by the operator when he is in his normal working position;
- the operator does not find himself in a dangerous situation when operating them.
The actuators of foot-operated control devices shall be selected and installed so that:
- are easily reachable by the operator when he is in his normal working position;
- the operator does not find himself in a dangerous situation when operating them.
Furthermore, they must be included in a specific field of vision of the operator.
BUTTON COLOR
The colors for the START buttons are white, gray, or black, with a preference for white. Green is also permitted. Red cannot be used.
Red color should be used for EMERGENCY stop or interrupt buttons. Yellow background with red button should be used for EMERGENCY only.
The colors for STOP buttons are black, gray or white, with black being preferred. Green shall not be used. Red is also permitted, but it is recommended that it not be used near an emergency operation device. Green shall not be used.
White, gray, and black are the preferred colors for START and STOP buttons. Red, yellow, or green should not be used.
White, gray, or black are the preferred colors for buttons that cause operation when pressed and stop when released (inching or jogging motion). Red, yellow, and green should not be used.
RESET buttons shall be blue, white, gray, or black. When also used as STOP/OFF buttons, white, gray, or black shall be used, with black being preferred. Green shall not be used.
The yellow color is reserved for abnormal conditions, such as the interruption of the automatic work cycle.
Where the same colours white, grey, or black are used for several functions (e.g. white for start and stop actuators) an additional coding shall be used to distinguish them, e.g. position or symbol.
LIGHT SIGNAL COLORS (e.g. LIGHT TOWER)
The colour shall be chosen taking into account the information to be provided. The colours of the indicating devices and actuators shall be in accordance with the table. The use of colours on the electrical equipment of machines shall be in accordance with IEC 60204-1.
Safety and contrasting colours used in safety signs shall comply with ISO 3864-1. In the case of emergency stop actuators, the use of contrasting colours shall comply with ISO 13850.
Traffic lighting
All internal company traffic routes must be provided with sufficient natural or artificial lighting, suitable for the purpose.
The required illuminance values vary depending on the location.
