SLAAER4 March   2025 AFE781H1 , AFE782H1 , AFE881H1 , AFE882H1 , DAC8740H , DAC8741H , DAC8742H

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 The 4-20mA Loop
    2. 1.2 The HART Protocol
      1. 1.2.1 Adding HART to the 4-20mA Loop
      2. 1.2.2 HART FSK
  5. 2AFE882H1 EVM-Based HART Transmitter
    1. 2.1 AFE882H1 HART Modem
    2. 2.2 AFE882H1 Evaluation Module
    3. 2.3 HART Transmitter Construction
      1. 2.3.1 Detailed Schematic
        1. 2.3.1.1 Input Protection
        2. 2.3.1.2 Start Up With Low-Dropout Regulator
        3. 2.3.1.3 Voltage-to-Current Stage
        4. 2.3.1.4 Voltage-to-Current Calculation
        5. 2.3.1.5 HART Signal Transmission
        6. 2.3.1.6 HART Input Protection
        7. 2.3.1.7 HART Transmitter Board
        8. 2.3.1.8 Current Consumption
      2. 2.3.2 HART Protocol Stack
  6. 3HART Testing and Registration
    1. 3.1  HART History and the FieldComm Group
    2. 3.2  HART Testing Overview
      1. 3.2.1 HART Protocol Specifications
      2. 3.2.2 HART Protocol Test Specifications
      3. 3.2.3 Field Transmitter Device Testing
    3. 3.3  HART Test Equipment
    4. 3.4  HART Physical Layer Testing
      1. 3.4.1 FSK Sinusoid Test
      2. 3.4.2 Carrier Start and Stop Time Tests
      3. 3.4.3 Carrier Start and Stop Transient Tests
      4. 3.4.4 Output Noise During Silence
      5. 3.4.5 Analog Rate of Change Test
      6. 3.4.6 Receive Impedance Test
      7. 3.4.7 Noise Sensitivity Test
      8. 3.4.8 Carrier Detect Test
    5. 3.5  Data Link Layer Tests
      1. 3.5.1 Data Link Layer Test Specifications
      2. 3.5.2 Data Link Layer Test Logs
    6. 3.6  Universal Command Tests
    7. 3.7  Common-Practice Command Tests
    8. 3.8  Device Specific Command Tests
    9. 3.9  HART Protocol Test Submission
    10. 3.10 HART Registration
  7. 4Summary
  8. 5Acknowledgments
  9. 6References

3.6 Universal Command Tests

The HART test system also runs the universal command tests of the application layer (UAL) starting from the hartmenu application. The universal command specification is defined under HCF_SPEC-127. These tests verify the application layer of the protocol and check the universal HART commands supported by the transmitter. The UAL test specification is defined by HCF_TEST_3. The test setup is the same as the DLL test setup, and also uses the HART test system to send commands to the transmitter. These tests verify the following functions of the applications layer:

  • Verify Support for All Universal Commands. These tests scan for the range of universal commands from 0 to 31 and look for a proper response.
  • Read Dynamic Variables. These tests check the responses to commands 1, 2, 3, and 9 for dynamic variable.
  • Verify Write Commands. The write tests check initial values, and subsequent write values. This tests the results of different data fields.
  • Verify Configuration Read Commands.
  • Confirm Write Protect. This is a test of the write protect into the transmitter (if this function is supported).
  • Test Cold Start Bit. The controller must be able to detect a cold start (i.e. a power failure).
  • Read Device Variables. This test verifies the proper operation of command 9.
  • Test the Configuration Changed Bit. This test verifies support for and proper operation of command 38 and checks a configuration changed counter to reset the status bit.
  • Support for Command 48, Read Additional Device Status. This test verifies support for command 48 and checks the ability to reset the More Status Available bit.

The end of the tests available require some user intervention for setting the cold start bit and checking the more status available bit.

Table 3-10 lists the tests run by the HART test system to verify support for universal commands and the results of the test.

Table 3-10 UAL Command Test List and Results
TEST NUMBERDESCRIPTIONRESULT
UAL000Confirm all universal commands are supportedPass
UAL001Read dynamic variables (commands 1, 2, and 3)Pass
UAL005Write messagePass
UAL006Write tag descriptor and datePass
UAL007Verify command 14 and 15 responsePass
UAL008Verify final assembly numberPass
UAL009Verify write protectNot applicable
UAL010Verify cold start bitPass
UAL011Read device variables (command 9)Pass
UAL012Read dynamic variable classificationPass
UAL013Write long tagPass
UAL038Reset configuration changed flagPass
UAL048Read additional device statusPass

The HART stack programmed into the transmitter passes these tests, except that the write protect was not programmed into the functionality. For this verify write protect test (UAL009), the test is checked as Not applicable. The complete set of UAL tests take about 30 minutes to complete. As with the DLL tests, running the UAL tests enables a HART sniffer window and generates a set of test logs for these tests for the application submission.