Show-goers get DeviceNet Safety previews

The first products to support the safety version of DeviceNet have been previewed in exhibitions on both sides of the Atlantic, prior to their commercial launch next Spring. In the UK, Sick demonstrated several DeviceNet Safety products at the Drives & Controls Show, while in the US, Rockwell was showing pre-production versions of some of its DeviceNet Safety portfolio at its annual Automation Fair in Orlando, Florida.

Sick and Rockwell have been collaborating with Omron since October 2002 on the technology which is the first implementation of the CIP (Common Industrial Protocol) Safety system. This is designed to provide failsafe communications between devices such as safety I/O blocks, interlock switches, light curtains and safety PLCs.

CIP Safety allows both safety and standard devices to operate on the same network. It will also allow safety devices to communicate across other CIP networks such as ControlNet and Ethernet/IP, with no extra programming. Unlike some other systems, this routing function will not require safety-specific hardware such as specialised gateways and bridges.

DeviceNet Safety, which covers applications up to SIL (Safety Integrity Level) 3, can be implemented with or without a dedicated safety PLC. It uses message redundancy and cross-checking to guarantee that safety messages are transmitted reliably and are received in a predetermined time.

It allows particular sections of a plant to be shut down, allowing production to continue elsewhere. So, for example, if a safety sensor in a robotic cell raises an alarm, or if the system`s diagnostics indicate that the sensor is misaligned, the shutdown can be limited to that cell.

At Telford, Sick was previewing an IP20 DeviceNet Safety network controller, and remote I/O bus nodes. The controller (above) will integrate any combination of safety input and actuator devices into a DeviceNet Safety network, using local or remote safety I/O. It can handle up to eight safety-capable dual channels.

Sick`s remote bus nodes will be available either in IP20 enclosures for use in cabinets, or in IP67 enclosures for use close to a machine without needing extra protection. Up to 14 sensors and actuators can be linked to a network using just one field bus address.

At its Automation Fair in Florida, Rockwell was previewing a variety of DeviceNet Safety products, including controllers and I/O, prior to their launch in April 2005.