The Babel Buster BB2-2011 Modbus RS-232 to LonWorks gateway connects a single Modbus RTU RS-232 device to a LonWorks network, mapping Modbus RTU registers to LonWorks network variables. The BB2-2011 is a standard LonWorks node with bindable network variables. The BB2-2011 Modbus RS-232 to LonWorks gateway can be a Modbus RTU master or slave.

The BB2-2011 can map scalar or structured network variables to Modbus registers, with structured network variables being distributed to multiple Modbus registers. Packed Modbus holding registers can be mapped to multiple LonWorks network variables for reading or writing.

BB2-2011 Modbus RS-232 to LonWorks Functionality

Data objects associated with Network Variable Outputs will poll Modbus registers at the interval you specify, and provide the Modbus data to the LonWorks network as an NV update. Data objects associated with Network Variable Inputs will receive their data from the LonWorks network as an NV update. The received data will be written to the assigned Modbus registers periodically or upon NV update.

Feature Highlights
• Connect single Modbus RTU RS-232 device to LonWorks Network
• Modbus to LonWorks gateway is a standard Managed LonWorks Node
• Configurable as Modbus RTU Master or Slave
• 120 Network Variable Inputs, 120 Network Variable Outputs
• Based on FT 5000, no installation credits required
• Up to 400 Modbus registers
• Free configuration software, download from
• FCC/CE Mark, UL 916 Listed
• Software Included, No Drivers to Buy

BB2-2011 Modbus RS-232 to LonWorks Gateway

Babel Buster BB2-2011 Modbus RS-232 to LonWorks Gateway

Order code: BB2-2011
Retail price: $769.00

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Are you going in the right direction?

The BB2-2011 puts a Modbus device on a LonWorks network. Do you need to put a LonWorks device on a Modbus network instead? If so, you want the BB2-2011-NB.


LonWorks to Modbus Data Flow

Control Solutions’ Babel Buster® BB2-2011 is a bindable LonWorks® node that functions as a Modbus RTU RS-232 master/slave. A large number of data objects gives you flexibility in mapping Modbus registers to scalar or structured LonWorks network variables. Packed Modbus registers may be parsed to multiple network variables when reading. Multiple data objects may be packed into a single Modbus register when writing. All standard Modbus register types are supported.

Data objects associated with Network Variable Outputs will poll their assigned Modbus register at the interval you specify, and provide the Modbus data to the LonWorks network as an NV update.

Data objects associated with Network Variable Inputs will receive their data from the LonWorks network as an NV update. The received data will be written to the assigned Modbus registers periodically or upon NV update (user selected).

The BB2-2011 is most often used as a Modbus master, but it can operate as a slave. This makes it possible to put LonWorks devices on a Modbus network (but does still require binding and network commissioning with LonMaker or equivalent).

The Babel Buster BB2-2011 is the upgraded replacement for the legacy Babel Buster 232. The BB2-2011 provides four times the network variable capacity, faster processing speed, and requires no installation credits for installation in an LNS based network.

LonWorks to Modbus Configuration Tool

The Gateway Node Configuration Tool is the most user friendly LonWorks gateway configuration tool to date. Connect the gateway to your laptop via a USB cable - no need for any adapters or “dongles”, and no need to have a functional network on either side of the gateway for initial setup.

Import Modbus register lists formatted as CSV files. Create your register list using any standard spreadsheet program, save as CSV, then import. The tool will then automatically create and assign network variables. Next, you export an XIF file representing your device. The XIF includes all configuration property file data and is ready to import into LonMaker.

You can also import an XIF file of a LonWorks device you want to provide Modbus access to. The tool will automatically assign Modbus registers, which is especially useful if the gateway will be a Modbus slave.

LonMark Function Block for Modbus to LonWorks Gateway

The LonWorks Network Variables (NV’s) contained within the Babel Buster gateway are configured as standard sensor and actuator function blocks with user changeable network variable types. Each variable has been allocated the maximum of 31 bytes of memory, meaning any known LonWorks variable type (including UNVTs) can be used. The NV’s are bound to other nodes on the LonWorks network using LonMaker or other comparable network management tool.

NV to Modbus Translation Diagram

Many LonWorks network variables are a single data value, such as temperature. However, many other LonWorks network variables are ‘structured’, meaning a single variable contains several related data values such as in the HVAC status variable. Modbus registers, on the other hand, always contain exactly one and only one data value. This means a single structured LonWorks variable cannot be translated to a single Modbus register. The single structured LonWorks network variable must be translated to or from multiple Modbus registers.

The method of making structured LonWorks data available to Modbus involves intermediary data ‘objects’ in the Babel Buster gateway. The LonWorks network variable input data structure is dispersed to multiple data objects. These data objects are, in turn, made accessible as Modbus registers after appropriate data scaling and reformatting. The process is reversed for structured network variable outputs, with multiple data objects (Modbus registers) collected up and formatted into a single LonWorks structured variable.

BB2-2011 Connections
BB2-2011 Connections


BB2-2011 Features

• Read/Write Modbus registers via LonWorks® NV’s
    • 400 Data objects accessible as Modbus registers
    • 120 Network Variable Inputs
    • 120 Network Variable Outputs
• Supports structured network variables
• Free topology LonWorks network
• Based on FT 5000, no installation credits required
• 32-bit ARM co-processor for greater processing power
• Bidirectional LonWorks-Modbus communication
• Supports Modbus “coils”, input registers, holding registers
• 16, 32-bit Modbus registers, signed, unsigned, IEEE 754
• Support for “Mod10” 2, 3, and 4-register data formats
• Modbus (master) polling interval configurable per point
• Operation as Modbus slave also possible, user selectable
• USB connection directly to PC for configuration
• Configuration software provided at no extra charge
• Internal flash card for simplified firmware updates
• EIA-232 transceiver for ModusRTU
• Modbus RTU baud rates: 1200 to 38400
• Powered by 12-24V DC/AC 50/60 Hz
• Power Consumption: 0.1A @ 24VDC
• DIN rail mounting, 100mm H x 70mm W x 60mm D
• Pluggable screw terminal blocks
• Operating temperature, standard -25°C to +85°C
• Operating temperature, extended -40°C to +85°C
• Humidity 5% to 90% non-condensing
• FCC, CE Mark, UL 916 Listed


• BB2-2011 Data Sheet

• BB2-2011 User Guide

• BB2-2011 Support Package
Contains configuration tool software, USB driver, documentation. XIF files are generated by the configuration tool.

• Modbus Tutorial
Introduction to Modbus, including function codes, exception codes, register numbering.

• LonWorks Tutorial
Basic overview of LonWorks, and "why is it so complicated?"

BB2-2011 Video Library

Watch these videos for an introduction to configuring the gateway. It's easier than reading!

Introduction to LonWorks Modbus Gateway Configuration Tool

BB2-2011 Video - Introduction

Configuring LonWorks Gateway from CSV Register List

BB2-2011 Video - Configure from CSV register list

Configuring LonWorks Gateway from XIF File for Other LonWorks Device

BB2-2011 Video - Configure from XIF file

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