When configuring automated assembly lines, engineers must protect workers from dangerous moving equipment. No one should lose a finger to a press or get clocked by a fast-moving robot arm.
For simple applications, hard-wired systems with safety relays are sufficient. However, as the system grows to include more inputs and outputs, wiring becomes expensive and difficult to troubleshoot. Diagnostics are limited. If new functionality is needed, these systems require significant rewiring and new validation efforts. Hard-wired systems also limit the ability of engineers to create complex safety systems, such as multiple safety zones around a collaborative robot.
Fortunately, it’s possible to provide safety functions over a standard communication network, such as EtherNet/IP, an industrial network protocol that adapts the Common Industrial Protocol (CIP) to standard Ethernet.
Because CIP exists solely in the application layer of the OSI and TCP models, it’s easy to add high-integrity safety services and diagnostics without requiring special communications hardware. This leverages existing communications infrastructure and helps reduce life-cycle costs. This enhanced protocol is called CIP Safety, and it can co-exist with other communication protocols, like CIP Motion and CIP Security.
CIP Safety provides fail-safe communication between nodes, such as safety I/O blocks, safety interlock switches, safety light curtains and safety PLCs in safety applications up to Safety Integrity Level (SIL) 3, pursuant to IEC 61508 standards.
Safety application coverage in CIP provides the ability to mix safety devices and standard devices on the same network or wire for seamless integration and increased flexibility. Safety data in the device is packed into the CIP Safety protocol, which resides inside an Ethernet IP packet, which becomes an Ethernet frame. Since making a safety-rated network would be impractical, the CIP Safety protocol leverages the black channel principle, putting the intelligence in the end-devices instead of the network hardware. The end-devices perform the diagnostics on the CIP Safety protocol to detect each type of error that could occur in the network, so the device can still go to a safe state when an error occurs.
EtherNet/IP and CIP are managed by ODVA Inc., a global trade and standards development organization with more than 300 corporate members, including some of the world’s leading industrial automation companies.
One of those companies is Bosch Rexroth. Last year, the company’s drive-integrated SafeMotion machine safety platform received the ODVA’s CIP Safety over EtherNet/IP certification, adding to the company’s capabilities to support major safety automation buses, including CIP Safety on Sercos, PROFIsafe on PROFINET, and FailSafe over EtherCAT.
SafeMotion technology is available on Bosch Rexroth IndraDrive intelligent servo drives.
With this latest certification, SafeMotion can now be integrated into almost any new or existing machine automation architecture, giving machine builders more options in machine safety functionality. Adding safety capabilities in the drive can alleviate additional hardware and components.
SafeMotion can be used to monitor up to 20 safe and certified motion functions, such as safe torque off, safe brake control, safe direction and safe stop. It provides the maximum level of safety (Cat 4, PL e, SIL 3) for all functions.
Bosch Rexroth supports all major safety automation buses through a multi-Ethernet port on the drive, making it easy to specify one drive platform with a variety of options, regardless of the PLC. Using one bus system for both standard and safety communication also simplifies system architecture and reduces cabling and installation efforts for the machine builder.
With easy system integration, engineering staff aren’t required to manage additional hardware and software applications. The Bosch Rexroth drive and SafeMotion functionality work right out of the box, requiring no additional tuning. Base parameters typically work for all applications, saving installation time. Software, firmware, configuration, setup and features are identical across the entire Rexroth IndraDrive platform.
In addition, Bosch Rexroth integrates several free tools into their servo drives to help save time and costs with safety validation and required technical documentation, even across series machines. These tools include the machine acceptance test—which validates the SafeMotion functions—as well as the ability to create screen clips and plot velocity, position, monitoring and thresholds.
Certified SafeMotion functionality is available throughout the entire Rexroth IndraDrive series, from 100 watt to 4 megawatt drives.
For more information visit https://www.boschrexroth-us.com/drive-integrated-safety.