SLAAEH8 October   2024 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. 2AFE881H1 HART Modem
    1. 2.1 AFE881H1 HART Transmitter
    2. 2.2 Detailed Schematic
      1. 2.2.1 Input Protection
      2. 2.2.2 Startup Circuit
      3. 2.2.3 Voltage-to-Current Stage
      4. 2.2.4 Voltage-to-Current Calculation
      5. 2.2.5 HART Signal Transmission
      6. 2.2.6 HART Input Protection
      7. 2.2.7 Current Consumption
      8. 2.2.8 HART Transmitter Board
      9. 2.2.9 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 Remote 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. 4Other TI HART Modem Designs
  8. 5Summary
  9. 6Acknowledgments
  10. 7References

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 NUMBER DESCRIPTION RESULT
UAL000 Confirm all universal commands are supported Pass
UAL001 Read dynamic variables (commands 1, 2, and 3) Pass
UAL005 Write message Pass
UAL006 Write tag descriptor and date Pass
UAL007 Verify command 14 and 15 response Pass
UAL008 Verify final assembly number Pass
UAL009 Verify write protect Not applicable
UAL010 Verify cold start bit Pass
UAL011 Read device variables (command 9) Pass
UAL012 Read dynamic variable classification Pass
UAL013 Write long tag Pass
UAL038 Reset configuration changed flag Pass
UAL048 Read additional device status Pass

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.