Bus Terminal Controller series BX

Bus Terminal Controller series BX

The BX series Bus Terminal Controllers offer a high degree of flexibility. In terms of the equipment and performance range, the small controllers are positioned between the BC series Bus Terminal controller and the Embedded PC series CX. The concept of autonomous control, or of slave in a higher-level fieldbus system, was expanded from the BC. The housing design is based on that of the CX1000. The main features distinguishing BC and BX are the larger memory and the expanded interfaces.

The BX family Bus Terminal Controllers consist of a programmable IEC 61131-3 controller and the K-bus interface for the connection of the Beckhoff Bus Terminals and a fieldbus interface. Additionally, the BX devices are equipped with two serial interfaces: one for programming, the other for free utilisation. The device itself comprises an illuminated LCD display with 2 lines of 16 characters each, a joystick switch and a real-time clock. Further peripheral devices, e.g. displays, can be connected via the integrated Beckhoff Smart System Bus (SSB).

The Bus Terminals can be connected directly in the usual way. The comprehensive range of different I/Os enables any input signal to be read and any output signal that may be required to be generated. This small controller therefore enables a wide range of automation tasks to be solved, from garage door controllers to autonomous temperature control at injection moulding machines. The BX family is also particularly suitable for a modular machine concept. Within a network, the Bus Terminal Controller can exchange data with other machine components via the fieldbus interfaces. The real-time clock also enables decentralised applications, for which the day of the week or the time play an important role.

The areas of application of this series are similar to that of the BC series, but due to the larger memory the BX can execute significantly more complex and larger programs and can manage more data locally (e.g. history and trend data recording), which are then successively fetched over the fieldbus.

Fieldbus interface

The variants of the BX series Bus Terminal Controllers differ in terms of their fieldbus interfaces. Additionally, two serial interfaces are integrated for programming and for the connection of further serial devices. Five different versions cover the main fieldbus systems:

- BX5100: CANopen
- BX5200: DeviceNet
- BX8000: RS232 or RS485 (without fieldbus interface)
- BX9000: Ethernet TCP/IP


The BX devices are programmed according to the powerful IEC 61131-3 standard. Like all other Beckhoff controllers, the TwinCAT automation software is the basis for parameterisation and programming. Users therefore have the familiar TwinCAT tools available, e.g. PLC programming interface, System Manager and TwinCAT Scope. Data is exchanged optionally via the serial port (COM1) or via the fieldbus through Beckhoff PC Fieldbus Cards FCxxxx.


The configuration is also carried out using TwinCAT. The fieldbus interface, the SSB bus and the real-time clock can be configured and parameterised via the System Manager. The System Manager can read all connected devices and Bus Terminals. After the parameterisation, the configuration is saved on the BX via the serial interface. The configuration thus created can be accessed again later.


Due to the wide variety of interfaces for the connection of different devices, the BX series Bus Terminal Controllers enable cost-effective control.


Smart System Bus

The Smart System Bus (SSB) is a CANopen-based subsidiary bus system for the connection of CANopen slave devices to the BX. The project planning is carried out with the TwinCAT System Manager and then downloaded into the BX.


TwinCAT is used for programming. All 5 IEC 61131-3 languages are supported: AWL, FUP, KOP, AS, ST. The project file can be downloaded to the BX and later uploaded again. Additionally, an online change for faster and simpler programming and commissioning is possible.


The system is configured via the TwinCAT System Manager. Here, the fieldbus interface, the SSB bus and the real-time clock are configured and parameterised.

K-bus interface

This can be used for the connection of over 100 different I/Os from the Beckhoff Bus Terminal range: digital inputs with different filters, digital outputs, analog inputs and outputs with up to 16 bit resolution, thermocouple and RTD inputs, serial interfaces and encoder inputs.


The serial COM1 port RS232, alternatively a fieldbus interface, are available for programming.

Joystick switch

for parameterisation and diagnosis

LCD display

FSTN 2 x 16 lines display for diagnosis or own texts, illuminated


The COM2 interface is available for the connection of serial devices (RS232 or RS485). Various protocols can be implemented with the aid of function blocks, such as Modbus-RTU, RK512 etc. or also own protocols. The baud rate, stop bits and parity are freely selectable.

Real-time clock

A real-time clock (RTC) is suitable for decentralised time- or weekday-dependent applications. The clock can be set via TwinCAT or via the display and the configuration switch. The clock has a battery backup with a minimum lifetime of one year.