BZ-7400, BZ-7401, BZ-7402, BZ-7403, BZ-7404

Open Interface for HBK 2255 and B&K 2245

Enable new real-time remote control, integration and accessibility possibilities for you sound level meter, increasing the control you have over your data and reliability interfacing with third-party software

Richiedi un preventivo

All HBK 2255 and B&K 2245 sound level meter solutions are designed to be used when and where you have a job to do. Open Interface for HBK 2255 and B&K 2245 enables custom applications and third-party software to communicate with, control and stream data from HBK 2255 and  B&K 2245 sound level meters via our Web-XI protocol over Ethernet, Wi-Fi® or USB using standard web technologies. This level of control opens up a new range of possibilities for integrated setups, distributed measurement systems and working with your own or third-party software.

Open Interface for HBK 2255 and B&K 2245 can be used together with any HBK 2255 or B&K 2245 licence to provide access to all measurement features via Web-XI. For example, Open Interface for B&K 2245 installed on B&K 2245 with Enviro Noise Partner BZ-7301 enables communication between the sound level meter and a client for all measurement features of Enviro Noise Partner BZ-7301.


  • Integrate HBK 2255 or B&K 2245 into a setup acquiring measurement data using your own application
  • Access selected measurement features from a customized user interface to meet your requirements
  • Incorporate HBK 2255 or B&K 2245 into permanent installations for correlating sound data with other physical properties
  • Remotely control and acquire data simultaneously from multiple/distributed sound level meters
  • Monitor, in real time, sound parameters using one or more sound level meters as remote microphones
  • Stream discrete sound parameters, measurement audio, spectra and events
  • Perform product testing using customized sound measurement workflows
  • Acquire data from distributed sound measurement systems controlling multiple sound level meters


  • Setup triggers for various levels and events
  • Fast binary streaming format for efficient and continuous data transfer
  • GPS synchronization for clock setting
  • PC software for storage, viewing and reporting of sound level meter data (free to download in Links and Downloads)
  • Documentation of protocol specifications and a guide for programming
  • Example programs in C#/.Net, Python

Education and Research

  • Add accurate sound measurement to projects using simple REST commands
  • Integrate sound measurement into applications written in almost any language


  • TCP/IP networking, wireless (Wi-Fi) and wired (Ethernet, USB)
  • HTTP/HTTPS request methods (GET, PUT, POST and DELETE)
  • REST web service structure
  • mDNS and zero configuration networking
  • DHCP network management


Web-XI is a RESTful protocol developed by HBK to enable communication between the sound level meter and clients.

The Web-XI protocol uses JSON data formatting and relies on Internet-infrastructure protocols (TCP/IP and HTTP/HTTPS) for communication in all HBK 2255 or B&K 2245 applications. Using GET, PUT, POST and DELETE, you can control the sound level meter settings to fetch parameters and results, and set up WebSocket streams for Web-XI data. WebSocket streams use a compact and fully documented binary data format to ensure fast and efficient communication. With these streams, time-stamped measurement and system status data can be continuously pushed from your sound level meter to your application.

Web-XI is a RESTful service, making it is possible to communicate with HBK 2255 or B&K 2245 from any platform that supports HTTP requests and to develop the software using a variety of programming languages such as C#, Objective-C or C/C++ and Python.


The measurement capabilities of any HBK 2255 or B&K 2245 with Noise Partner BZ-7300 can be further customized for use in your own specialized or even unique setups by adding any combination of licences for Extended Broadband Analysis BZ-7401, Logging BZ-7402, Frequency Analysis BZ-7403 and MP3 Audio BZ-7404.  Additional measurement features can be enabled on HBK 2255 sound level meters with BZ-7540 Advance Logging or BZ-7451 Analysis Quality Audio licences. These licences may be used without the Open Interface for HBK 2255 or B&K 2245 BZ-7400 licence installed in order to access their specific features, but for a client connection, BZ-7400 must be installed.

The BZ-7400 series of licences add:

  • BZ-7400: Connect to HBK 2255 or B&K 2245 from any application via Web-XI
  • BZ-7401: Broadband parameters (LXE (SEL), LavS4/5 and LAFTeq) and Statistics parameters (LAYN and LAN)
  • BZ-7402: Logging at 1, 5, 10, 30 or 60 s intervals
  • BZ-7403: 1/1- or 1/3-octave band analysis (Leq, Lmax and Lmin)
  • BZ-7404: MP3 audio format
  • BZ-7540: Fast logging of broadband LXY and LXeq down to 1 ms intervals, fast logging of 1/n-octave LXY and LXeq down to 4 ms intervals, level and timer triggered audio recording, scheduled measurement timers and multi-frequency CIC (HBK 2255 only)
  • BZ-7451: Analysis quality 65 kHz, 24-bit audio recording, losslessly compressed with FLAC (HBK 2255 only)

A user guide with a description of all commands is provided in Links and Downloads, and code samples are available at GitHub®.