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Software-based Systems and Machine Safety Compliance
- Published: Tuesday, 02 February 2016 09:01
When ensuring compliance with machine safety regulations it’s important to consider all of the system options available to identify the most appropriate for your needs.
Kevan Cowley of Wieland Electric explains the key benefits of software-based systems
In recent years we have seen significant changes to the requirements for machine safety. These, in turn, have created opportunities for machinery manufacturers to take advantage of new hardware and software designs that not only ensure compliance but also reduce complexity to help with system design, installation and operation.
The most familiar of these is probably the Machine Safety Directive (as defined in either EN ISO 13849-1 or the alternative EN (IEC) 62061) but there are also specific standards relating to particular types of equipment. A good example of this is EN16500-2014, which relates specifically to balers that are used for compacting waste. Compliance with EN16500 is greatly facilitated by the use of the new modular, configurable safety control systems that have come on to the market in recent years.
This was clearly evidenced during a recent project involving a manufacturer of a wide range of balers for use in waste recycling. Clearly the company needed to ensure its machines comply with EN16500-2014, but at the same time wanted to achieve this the most straightforward and cost-effective way. The answer proved to be re-development of a safety and control system that makes use of the latest hardware and software products. This approach delivered a number of benefits, including achieving full compliance, reducing wiring requirements, reducing control panel sizes and ensuring control system standardisation throughout the company’s ranges.
At the heart of these newer, more advanced systems are modular, configurable safety control systems that use centralised input/output (I/O) systems to reduce the hard wiring requirement and therefore the overall complexity. Such systems deliver a wide range of benefits for all aspects of machine safety compliance.
However, it is important to bear in mind that wiring complexity can vary considerably between different types of modular safety systems.
There are essentially two types of modular safety control systems – mechanically configurable and software-based. Clearly, mechanically configurable systems tend to have more complex wiring so if the project criteria include reduction of complexity and cost, the preferred option will usually be a software system with centralised I/O.
In this respect, just as there is variation within modular systems overall, there is also variation in complexity between different types of software-based systems. So this also needs to be borne in mind, especially in relation to the complexity of the wiring requirements for monitoring faults.
Another important consideration is how much modularity is available. If a system has a fixed number of I/Os this may mean that the system does not exactly meet the project’s requirement for I/Os, so that it may be necessary to purchase more of these than are required. This is particularly likely to be issue in smaller applications and can even make the use of modular systems financially unviable, so that the other benefits of such systems are missed.
A higher degree of flexibility, with the ability to closely tailor the solution to a project’s specific requirements, comes with systems that offer the controller separately from the I/O module. This makes it very easy to match the I/O requirement precisely to the requirements of the system.
Increasingly, there is a requirement for machines to be integrated into a wider network. It is therefore essential to ensure that any software-based system is capable of communicating across a common protocol that meets your requirements. It should also be possible for the controller to send diagnostic information through these gateways.
Additionally, a software-based, networked system can incorporate a self-validating verification process to prevent mistakes and underpin compliance. Inclusion of date and time stamp verification is also of great assistance when compiling proof of what was installed. It is certainly a more efficient approach than the more traditional and time-consuming approach of producing written reports, diagrams and photographs for system verification.
Return on investment
Clearly any such investment in a software-based solution needs to offer a return, so the cost of the software will be a primary consideration in the majority of projects.
Some manufacturers charge a licence fee that covers basic functions, with extra charges for any additional functions that may be required. In contrast, other suppliers offer freely downloadable software with all of the functionality included as standard – which can make a significant difference to the business case for investing in such systems.
The important thing is to be aware of the variation with the general term ‘modular systems’ and to assess each of the features and functions that will impact on usability, cost and financial return.