Design considerations - Johnson Controls - LIT-12014421 - AD-1272 - Airflow Measuring Station - AFMS

AD-1272 Advanced Thermal Dispersion Probe Airflow Measuring System SA Bus Integration Application Note

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When you integrate the AD-1272 device, consider the following guidelines:

  • Install all AD-1272 equipment and ensure that the AD-1272 device is set up and operates correctly before you attempt to integrate the AD-1272 device into the GSAB network.
    Note: The correct operation of AD-1272 equipment is the responsibility of a Johnson Controls representative.
  • Ensure to set all device addresses on each AD-1272 device. Avoid SA Bus reserved addresses 0 to 3. Do not change the device address when you add the associated GSAB device in the CCT tool. For more information, refer to the AD-1272 Advanced Thermal Dispersion Probe Airflow Measuring System Installation Instructions (LIT No. LIT-12012552).
  • The communication parameters on the SA Bus are fixed. Ensure to set the following values on each AD-1272 device:
    • 38,400k baud
    • 8 data bits
    • No parity
    • 1 stop bit
  • The SA Bus is an RS-485 daisy-chain topology network that supports connections of up to 10 devices. Traffic considerations and power consumption can reduce that amount. The total power consumption for the SA Bus is limited to 240 mA on the SA Bus terminal block. If the total power consumption exceeds this limit, it may result in poor Bus communication and cause devices to go offline.
  • Ensure you have the correct JCPKG file that represents the specific BACnet MS/TP device. The JCPKG file includes the point list for a specific BACnet MS/TP device. The CCT tool and the JCPKG file add the device to the application when you configure the Equipment Controller.
    Note: You cannot configure GSAB integration without the device-specific JCPKG file.
  • Follow the SA Bus rules in the MS/TP Communications Bus Technical Bulletin (LIT-12011034).
  • Apply CCT Release Mode 10.7/Firmware 11.0 or higher when you create the CAF file.
  • If necessary, and if possible, set the Max Master parameter on the AD-1272 device to an appropriate value to avoid additional latency on the SA Bus.