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  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction to the HART Protocol
    1. 1.1 Different Forms of the HART Protocol
    2. 1.2 HART as an Enhancement to the 4-20 mA Loop
    3. 1.3 The HART FSK Signal
    4. 1.4 HART Configurations
    5. 1.5 HART Protocol Structure
      1. 1.5.1 HART Communication
      2. 1.5.2 HART Bytes
      3. 1.5.3 HART Data Frame Structure
        1. 1.5.3.1 HART Start Byte
        2. 1.5.3.2 HART Device Addressing
        3. 1.5.3.3 HART Commands
  5. 2HART Protocol and Test Specifications
    1. 2.1 The OSI Protocol Model
    2. 2.2 HART Protocol Specifications
    3. 2.3 HART Test Specifications
  6. 3TI HART Enabled Devices
    1. 3.1 TI DACs with HART Connections
    2. 3.2 TI HART Modems
  7. 4Conclusion
  8. 5References

2.3 HART Test Specifications

The following is a list of HART protocol test specifications. These test specifications describe the details of HART testing for the different layers of the protocol. The test specifications describe how the tests are constructed and what different test failures look like.

For the test specifications, only the table of contents can be viewed online at the given website. Non-member companies must purchase the bound book.

The four test protocols govern the tests required for HART registration. The physical layer test specification covers the physical aspects of the HART signal on the loop. This covers the Frequency Shift Key (FSK) signal shape and frequency, the tolerable noise within the frequency bands of operation, the timing between the FSK and digital signals to the board, and the output impedance of the board itself.

The token-passing data link layer tests (DLL tests) govern the communication between the HART host and the remote transmitter. Universal command tests (UAL tests) cover commands that must be supported by all HART devices. Common-practice command tests (CAL tests) cover commands that are often implemented in HART devices. The DLL, UAL, and CAL tests require a specialized HART tester that transmits different commands in different formats to check the response of the device.