When designing a safety solution for a machine or application, a fundamental consideration is whether to implement it as a standalone or network safety solution. Standalone safety involves wiring safety devices point-to-point to a safety relay or controller, which in turn is wired to a contactor or a device that disconnects primary power to a machine. Network safety, on the other hand, collects the safety devices and connects them to a network safety system via a field bus that uses a communications gateway, a safety CPU, and safety I/O.
Network safety has multiple advantages over standalone safety. First and foremost, it is a highly effective way to mitigate risk. In addition to this, network safety becomes a key factor of a high performing, future-ready manufacturing facility thanks to its ability to improve automation efficiency and boost throughput.
Why are there so many industrial networking protocols?
As there are several different manufacturers, there are also several unique, independent solutions to solve communication issues. In particular, manufacturers needed their operations to be:
• Capable of responding in real time.
• Deterministic.
• Reliable/redundant.
• Secure.
• Safe.
• Ruggedised.
The process of converging protocols prompted an effort to bring together the best practices and standardise communications. The cornerstone of interoperability is a standard communications protocol. EtherCAT (ECAT) is an example of a higher level networking protocol that uses a multiple layer protocol model to interwork with many Fieldbus protocols.
Choosing the right safety network configuration
While various configurations can address network safety, choosing the correct one is essential in optimising automation efficiency and reducing safety risk. A safety risk assessment is the primary way to establish the correct safety needs and the correct configuration.
Automation architecture must provide control, configuration capabilities and data collection. The two leading network safety architectures are Fail Safe over EtherCAT (FSoE) and Common Interface Protocol Safety (CIP Safety). EtherCAT technology allows for interoperability between participating vendor devices. It is faster, has a wider bandwidth, and supports processing on the fly. CIP Safety provides failsafe communication between nodes and enables interoperability between various automation and safety vendors.
Eight types of network errors must be mitigated for proper functional safety communications. These are:
1. Corruption of the signal.
2. Unintended repetition of the message.
3. Incorrect sequence of the message.
4. Loss of the message.
5. Unacceptable delay of the message.
6. Insertion of another unintended message.
7. Masquerade the message.
8. Addressing the message as intended.
In summary, networking safety is the culmination of maximised safety risk mitigation, improved automation efficiency, and increased factory output. Omron’s safety solutions tie into Industry 4.0 level performance of industrial automation. Safety was once considered a mandatory compliance issue, but it is now an integral part of elevated performance.
From point-to-point connections to a fieldbus, networking the safety system helps make the operation robust and future-proofed. Omron’s safety solutions can provide the answer to each of the possible configurations and leading communications protocols that exist.
| Tel: | +27 11 579 2600 |
| Email: | info_sa@omron.com |
| www: | www.industrial.omron.co.za |
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