TB20-C, Bus coupler


TB20-C, Buskoppler ModbusTCPTB20-C, Buskoppler ModbusTCP Front
TB20-C, Buskoppler ModbusTCP
TB20-C, Buskoppler ModbusTCP Front

The Modbus/TCP bus coupler makes it possible to access data from peripheral modules using the Modbus/TCP protocol, but can accommodate up to 64 modules of any kind connected in series with the bus coupler.
The Modbus/TCP bus coupler features an integrated two-port switch that allows for star and line topology configurations.
A large I/O image table size of 2 kbytes makes it possible to implement comprehensive and complex systems.
The control and status registers can be used to configure and monitor the coupler's behavior with Modbus/TCP.
TB20 ToolBox can be used to easily configure the system structure and the various module parameters, and transfer the corresponding settings to the coupler.

A functioning TB20 configuration will always require a bus coupler and at least one peripheral module. The bus coupler supports hot-swapping for replacing modules during operation.

  • Modules can be replaced during operation (hot-swapping)
  • 24 V DC power supply 
  • Integrated power supply unit for powering peripheral modules (2.5 A) 
  • Supplies the system’s I/O voltage (24 VDC) 
  • USB device port for online diagnostics, configuring parameters, setup, and firmware updates with "TB20 ToolBox"
  • TB20 ToolBox simulation for commissioning the I/O system without a higher-level controller in order to test the functionality (I/O check)
  • Concealed "factory reset" switch for restoring the module to its factory settings• Connection watchdog for connection monitoring
  • Simultaneous access to up to 10 stations (TCP connections)
  • Integrated two-port switch
  • Up to 64 peripheral modules
  • 2 x RJ45 connections
  • 2048 bytes of input, 2048 bytes of output data
  • 126 bytes of parameter data per module
  • The coupler's behavior can be configured using control registers
  • The coupler's status can be read out using status registers
  • 7 LEDs, one of them bi-color

Download PDF datasheet
General information
Order number 600-170-1AA11
Article name TB20-C, Modbus/TCP bus coupler
Scope of delivery Bus coupler ModbusTCP, 24 V power supply connector, bus cover element, base module
Dimensions (DxWxH) 110 x 35 x 73 mm
Weight Approx. 115 g
Modbus interface
Number 2
Protocol ModbusTCP
Transmission rate 10/100 Mbps, automatic detection
I/O image size 2048/2048 bytes
Parameters per module 126 bytes
Connection RJ45
integrated switch Yes
Supports Modbus function codes 1, 2, 3, 4, 5, 6, 15, 16, 22, 23
TCP connection 10 stations
USB interface
Number 1
Protocol Full-speed USB 1.1 device
Connection Mini-USB
Isolation voltage 1.5 kV
Electrical isolation Yes
Number of modules that can be connected in series 64
Voltage supply 24 VDC, 18–28 VDC
Current draw
Current draw without modules (internal) 75 mA
Power supply for modules 5 V DC, max 2.5 A
Power dissipation Max. 8 W
Installation position Any
Ambient conditions
Ambient temperature 0 °C … +60 °C
Transport and storage temperature -20 °C … +80 °C
Relative air humidity 95 % r H without condensation
Protection rating IP 20
Certifications CE, UL
Surrounding Air Temperature 0 °C … +50 °C
Pollution degree 2
Noise immunity DIN EN 61000-6-2 “EMC Immunity”
Interference emission DIN EN 61000-6-4 “EMC Emission”
Vibration and shock resistance DIN EN 60068-2-8:2008 “Vibration”, DIN EN 60068-27:2010 “Shock“
RoHS Yes

Technical Documentation

 Name Version Size Tags
TB20, Manual ModbusTCP Bus Coupler 1 4 MB


 Name Version Size Tags
TB20. Distributed fieldbus I/O system 11-2017 8 MB


 Name Version Size Tags
TB20, USB Driver 1.20 7 KB

Planning Tools

 Name Version Size Tags
TB20 ToolBox v1.48 12 MB
TB20, Macros for EPLAN Electric P8* from V2.0 in EDZ format 07.02.2018 84 MB
TB20, STEP files 1.00 8 MB

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The 24 V power supply connector, the bus cover element, and the base module are included as standard.

“TB20 ToolBox” makes it easy to plan the system. Integrated terminal mapping, system width calculations, and current-carrying capacity monitoring all make it possible to quickly design systems without making any mistakes.