Technical Paper Abstract
The emergence of Industry 4.0 has accelerated the adoption of reconfigurable and software-defined manufacturing systems. These systems rely increasingly on programmable controllers, distributed input/output devices, industrial Ethernet networks, and dynamically integrated safety functions. Functional safety communication profiles such as CIP Safety apply the black-channel principle defined in IEC 61784-3 [2]. Under this principle, standard communication infrastructure may be used to transport safety-related information, provided that an independent end-to-end safety communication layer detects or controls the assumed communication errors.
CIP Safety is specified in Volume 5 [1] of the ODVA CIP Networks Library and standardized as Functional Safety Communication Profile 2/1 in IEC 61784-3-2 [2]. It uses safety Cyclic Redundancy Checks (CRCs), timestamps, rollover counts, time-expectation monitoring, producer and consumer identification, redundant data encoding, cross-checking, and connection supervision. Collectively, these mechanisms address communication failures [7] such as message repetition, loss, insertion, incorrect sequence, corruption, delay, unintended coupling, increased data age in bridges, and addressing errors.
This paper evaluates the coverage provided by these mechanisms within the CIP Safety producer–consumer model through Communication Failure Mode and Effects Analysis (Communication FMEA) [4]. The assessment considers unicast and multicast connections, the required Extended Format, and the deprecated Base Format where legacy compatibility remains relevant. The Communication FMEA yields integration assumptions that are subsequently evaluated against product-level implementation faults, including memory corruption, partial DMA overwrite, timestamp-processing errors, scheduling faults, incorrect configuration handling, and corruption occurring before cyclic redundancy check (CRC) generation or after message validation. Product level FMEA thereby supports traceability and validation of those integration assumptions.
The analysis demonstrates CIP Safety provides strong detection of communication-channel errors. To support complete product or system safety, the paper serves as a guidance for root-cause identification, diagnostic granularity, system availability, internal non-interference, semantic validation of process values, and allocation of the complete system reaction time. The paper therefore proposes an assessment methodology that maps communication FMEA, product FMEA [4], Functional Requirement Specification identifiers, and applicable test evidence. The methodology also evaluates system-level architectural controls alongside the protocol and its interface requirements, including fault-injection testing, to provide illustrative examples for product developers, safety assessors, and standards working groups (WGs).
Keywords
Availability; Black-channel principle; CIP Safety; Closed communication system; Communication failure classes; Communication FMEA; Cyclic Redundancy Check; Extended Format; Functional safety; Integration faults; Multicast; Product FMEA; Residual error; SC3; Single-cast; System reaction time.
Paper and presentation from the 2026 ODVA Industry Conference & 24th Annual Meeting: to be published November 2
Riya Rahul Shah, Senior Functional Safety Lead, Utthunga Technologies
Shyam Sundar Pal, Firmware Architect, Utthunga Technologies