Green Hills' industrial safety platform includes RTOS nearing SIL-3 certification
Integrity-61508's system architecture provides protected address space partitions, allowing developers to create and deploy applications with a mix of safety integrity levels on one microprocessor.
At ISA Expo 2005 in Chicago in late October, Green Hills Software Inc. (GHS) introduced its "Platform for Industrial Safety"—a complete software development and deployment solution for safety-critical industrial devices. Applicable devices include process controllers; programmable logic controllers (PLCs); and flame, gas, and temperature sensors. Core of the platform is new, royalty-free Integrity-61508 Real-Time Operating System (RTOS), which is in final stages of certification by TÜV to International Electrotechnical Commission (IEC) standard 61508 at Safety Integrity Level 3 (SIL 3). Full certification is expected by year-end 2005, says GHS.
IEC 61508 is an international standard addressing functional safety of electronic systems. Its premise is that no single fault of a device may result in a dangerous failure, with detected faults used to prevent failure (via trip/shutdown). SIL levels (1, 2, 3, and 4) are defined on basis of probability of a dangerous failure over time. SIL 3 rating is considered the highest risk reduction level achievable using a single programmable electronic system.
Certification of Integrity-61508 RTOS focuses on industrial automation, processor control, and automotive industries. Previously, Integrity-178B has received FAA DO-178B Level certification for safety-critical applications in commercial and military avionics. A systematic development process is needed to meet IEC 61508 requirements. The process emphasizes requirements traceability, criticality analysis, and validation.
Dan Mender, Green Hills director of business development, differentiates the company's Platform for Industrial Safety from other approaches. "In traditional solutions, critical and non-critical subsystems are usually totally separated, requiring separate resources to be expended for each, for example, power supplies. Green Hills' approach allows critical- and non-critical elements to run on one microprocessor (MPU), with appropriate partitioning and boundaries between them fixed for reliability," he told Control Engineering . Another differentiator for the safety platform is that users do not have to develop their own operating system and can avoid the time and cost of certification, explains Mender. "It's an RTOS plus software, and software makes the platform unique."
Integrity-61508 is said to be the first RTOS that provides complete support for multiple levels of IEC 61508 functional safety running concurrently on a single MPU. This benefits users, for example, through reduced hardware costs, physical footprint, power, and heat dissipation requirements. In the past, manufacturers had to certify all software running on a processor to the most stringent safety level required by any component. Such "federated" distributed systems had to be deployed to physically separate software at different functional safety levels. While this approach minimized certification cost and risk, it increased overall system cost and complexity, explains Mender.
Because of secure partitioning capability—for time, space, and resources between applications—in Integrity-61508 RTOS, each software partition can be certified at its appropriate SIL, eliminating the need for separate physical systems or to certify code beyond the required safety level. Industrial device manufacturers benefit from minimizing the software and documentation they must develop for their end products' safety certifications.
Besides Integrity-61508 RTOS, Platform for Industrial Safety includes:
Multi development environment—GHS' powerful and complete set of tools for optimizing reliability, performance, cost, and time-to-market of device software;
Full set of safety documentation, which is required for certification of the final device (safety manual, TÜV certification report, and TÜV SIL 3 certificate for Integrity-61508, as well as defect notification service); and
Optional middleware, Integrity-61508 source code, certification evidence, and services. For more details on options, see GHS' Web site.
When certification is complete (projected by year end), GHS' Platform for Industrial Safety will be available for a variety of processors—ARM ( ARM Corp. ); Blackfin ( Analog Devices ); ColdFire ( Freescale Semiconductor ); MIPS ( MIPS Technologies ); PowerPC ( IBM/Freescale ); and StrongArm, x86/Pentium, and XScale ( Intel Inc. ). Pricing for the platform starts $22,400 for a single user, enterprise license, with no run-time royalty fees for deployment. Single product, product line, and subscription licensing is also available.
Frank J. Bartos, executive editor, Control Engineering