SFFS779 December 2024 TMS320F28P550SJ
Information redundancy techniques can be applied using software as an additional runtime diagnostic. There are many techniques that can be applied, such as a readback of written values and multiple reads of the same target data with a comparison of results.
To provide diagnostic coverage for network elements outside the C2000 MCU (wiring harness, connectors, and transceiver) end-to-end safety mechanisms are applied. These mechanisms can also provide diagnostic coverage inside the C2000 MCU. There are many different schemes applied, such as additional message checksums, redundant transmissions, time diversity in transmissions, and so forth. Most commonly, checksums are added to the payload section of a transmission to verify the correctness of a transmission. The checksums, sequence counter, and timeout expectations (or timestamp) are then included with the original data, in addition to any protocol-level parity and checksums. As these are generated and evaluated by the software at either end of the communication, the whole communication path is safed, resulting in end-to-end safing.
Any end-to-end communication diagnostics implemented must consider the failure modes and potential mitigating safety measures described in IEC 61784-3:2016 and summarized in IEC 61784-3:2016, Table 1.