Overview
ISO 16844-2:2022 is an international standard specifying the recording unit communication interface for tachograph systems installed in road vehicles. This third edition update focuses exclusively on the electrical interfaces of the data and service connectors used by digital tachographs, excluding the electrical interfaces associated with CAN-based in-vehicle networks. It serves as a critical guideline for manufacturers and developers to ensure consistent, reliable communication between a vehicle’s recording equipment and external interfaces, facilitating proper data access and control.
The digital tachograph captures detailed data on driver activities and vehicle operations, providing valuable information to drivers, transport companies, authorities, and workshops. ISO 16844-2:2022 defines connector specifications, electrical requirements, and signal characteristics fundamental to the interface’s functionality.
Key Topics
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Connector Standards
The recording equipment connector must comply with ISO 16844-1, ensuring compatibility across tachograph systems. The connector is divided into two parts:
- Part A: Used for power supply and CAN connection, with electrical details harmonized with ISO 16844-4.
- Part B: Handles tachograph to motion sensor electrical connections with specific voltage, pulse, and frequency parameters.
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Electrical Requirements
Precise voltage levels, current values, and signal characteristics are specified for various pins on the Part B connector. These include:
- Positive and negative power supply pins.
- Speed signal and real-time data pins.
- Speed pulse output with defined pulse durations and frequencies.
- Optional distance signal output providing pulses representing movement increments.
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Signal Timing and Circuitry
Detailed timing diagrams and circuit schematics demonstrate signal delays, jitter allowances, and pulse output behavior to standardize communication reliability. Relationships between vehicle speed, tachograph constant, and pulse timing are defined with formulae ensuring consistent data interpretation.
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Scope Exclusions
This standard does not address electrical interfaces linked directly to CAN-based networks inside vehicles, which are covered in other parts of the ISO 16844 series.
Applications
ISO 16844-2:2022 is essential for:
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Tachograph Manufacturers
Designing recording units that adhere to international electrical interface standards for interoperability and regulatory compliance.
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Vehicle OEMs
Implementing tachographs with interface connectors meeting specified electrical requirements to ensure seamless integration with in-vehicle sensors and external diagnostic systems.
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Transport Companies and Regulatory Authorities
Accessing digital tachograph data for driver monitoring, compliance auditing, and transport safety enforcement, relying on standardized interfaces to read and download data securely.
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Workshops and Service Providers
Utilizing compatible equipment to service, calibrate, or inspect tachographs via defined data and service connectors.
Related Standards
- ISO 16844-1: Defines the recording equipment data and service connector physical and mechanical specifications.
- ISO 16844-3: Covers the communication interface between the motion sensor and the recording equipment.
- ISO 16844-4: Specifies the CAN-based data interface including parameter groups for broader vehicle communication.
- ISO 16844-7: Addresses data identifiers for optional service interfaces.
- Regulation (EU) No 165/2014: European regulation stipulating requirements for recording equipment in road transport enforcement.
By following ISO 16844-2:2022, stakeholders in the commercial transport and vehicle manufacturing sectors can ensure tachograph systems communicate correctly and comply with international standards. This contributes to safer transport operations, effective driver activity monitoring, and regulatory adherence worldwide.
Open preview (PDF)Road vehicles — Tachograph systems — Part 2: Recording unit communication interface