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

3.7 Common-Practice Command Tests

The last of the HART tests verify that common-practice commands of the application layer (CAL) are implemented in the transmitter. The CAL test specification is described by HCF_TEST_4. These tests check for highly-recommended commands that are implemented in many HART devices. Here is a basic list of common-practice commands that can be implemented in HART devices and tested as part of the CAL tests:

  • Read selection of up to four dynamic variables
  • Write damping time constant
  • Write device range values
  • Calibrate (set zero, set span)
  • Set fixed output current
  • Perform self-test
  • Perform host reset
  • Trim primary variable zero
  • Write primary variable unit
  • Trim DAC zero and gain
  • Write transfer function (square root/linear)
  • Write sensor serial number
  • Read or write dynamic variable assignments

Table 3-11 shows the set of common-practice command tests run by the HART tester. While the transmitter designed in this application note uses a HART stack that shows functionality of the device, this design is not a full-functioned device used as a real transmitter in an application. Many commands have been implemented, but not all are supported from this list of tests. This complete set of CAL tests take about 4 hours to complete.

Table 3-11 CAL Command Test Results
TEST NUMBER DESCRIPTION RESULT
CAL000 Checks for common practice commands Pass
CAL001 Write protect test Not implemented
CAL033 Read device variables Pass
CAL034 Write primary variable damping value Pass
CAL035 Write primary variable range values Pass
Primary variable units code unaffected by command 35 Pass
CAL036 Set primary variable upper range value Not applicable
CAL037 Set primary variable lower range value Not applicable
CAL040 Enter/exit fixed current mode Pass
CAL041 Perform self test Pass
CAL042 Perform device reset Pass
CAL043 Set primary variable zero Not applicable
CAL044 Write primary variable units Pass
CAL045 Trim loop current zero Pass
CAL046 Trim loop current gain Pass
CAL047 Write primary variable transfer function Not applicable
CAL049 Write primary variable transducer serial number Not applicable
CAL050 Read dynamic variable assignments Not applicable
CAL051 Write dynamic variable assignments Not applicable
CAL052 Set device variable zero Not applicable
CAL053 Write device variable units Not applicable
CAL054 Read device variable information Pass
CAL055 Write device variable damping value Not applicable
CAL056 Write device variable transducer serial number Not applicable
CAL060 Read analog channel and percent of range Not applicable
CAL062 Read analog channels Not applicable
CAL063 Read analog channel information Not applicable
CAL064 Write analog channel additional damping value Not applicable
CAL065 Write analog channel range values Not applicable
CAL066 Enter/exit fixed analog channel mode Not applicable
CAL067 Trim analog channel zero Not applicable
CAL068 Trim analog channel gain Not applicable
CAL069 Write analog channel transfer function Not applicable
CAL070 Read analog channel endpoint values Not applicable
CAL071 Lock device Not applicable
CAL072 Squawk Pass
CAL073 Find device Not applicable
CAL074 Verify I/O system commands Not applicable
CAL078 Command aggregation Not applicable
CAL079 Write device variable Not applicable
CAL080 Verify device variable trim commands Not applicable
CAL091 Trending Not applicable
CAL101 Subsystem burst mode Not applicable
CAL103 Support for multiple burst messages Pass
CAL104 Smart data publishing Pass
CAL107 Write burst device variables Pass
CAL108 Write burst mode command number Pass
CAL109 Burst mode control Pass
CAL115 Event notification Not applicable
CAL512 Country code Not applicable
CAL518 Location description Not applicable
CAL520 Process unit tag Not applicable
CAL523 Read condensed status mapping array Not applicable
CAL524 Manipulating condensed status map Not applicable
CAL526 Status simulation Not applicable

As with the DLL and UAL tests, running the CAL tests from hartmenu generates a set of logs for the registration submission.