The global objective of the logical and temporal program flow monitoring is given in the safety standard IEC 61508-7, Annex A.9 as "Temporal and logical program sequence monitoring":
"To detect a defective program sequence. A defective program sequence exists if the individual elements of a program (for example software modules, subprograms, or commands) are processed in the wrong sequence or period of time, or if the clock of the processor is faulty."
This common safety requirement is the purpose of the product Safety Add-Ons. The following video gives you an introduction to the Safety Add-Ons:
The Safety Add-Ons allow monitoring and checking each of the objectives (logical sequence and timing) individually. To achieve the highest diagnostic coverage levels, the combination is compelling in detecting potential defective program sequences.
Logical Program Flow
Program Flow Control
The program flow safety measure is a measure that is classified "highly recommended" in all safety standards. The logical program flow control performs logical checks for system functionalities. Such a system functionality can be a single function, a group of operations, or RTOS tasks.
The program flow control detects the following failure scenarios:
Temporal Program Flow
Time Budget Monitoring
We combine the temporal program flow monitoring most often with the logical program flow control to achieve the program flow safety measure's completeness. The temporal program flow monitoring performs timing-related checks in systems the static function scheduling.
The time budget monitor detects the following scenarios:
The end-to-end protected communication (E2E) is an additional method that comes in place when you need to transfer safe data via unsafe communication channels. The data protection is added directly into the transferred data enabling the receiver to identify any communication problem.
The E2E protection detects all possible communication faults:
Ready to Use
Since the requirements for these modules are originated from a safety standard, it is a natural choice that we perform a pre-certification for these modules.
Program Flow Monitor
The program flow monitor checks the logical program sequence.
Time Budget Watchdog
The time budget watchdog provides checking of the actual runtime consumption.
This module provides the calculation for cyclic redundancy checksums.
This module provides the communication protection of safety data.
Protect your Investment
The Safety AddOns are designed to provide standard conform safety measures for any hardware with any modern cross-compiler. The integration into the Flexible Safety RTOS is part of this component. The usage in other operating systems is simple and examples are prepared when using the E2E communication between multiple cores with different safety capabilities.
You get proven algorithms as part of the Safety AddOns, ready for use with a pre-certification for multiple use cases:
The delivered Safety AddOns are independent in many ways. This allows maximum possible flexibility in your project design:
The Safety AddOns comes with guidance on how to achieve the target diagnostic coverage in the extensive documentation.
Let's talk about your use-cases and potential benefits from this module in your system architecture.