The BK3120 is a compact industrial Bus Coupler manufactured by BECKHOFF. It serves as the primary communication gateway within modular I/O topologies, connecting upper-level PROFIBUS DP fieldbus networks to lower-level K-Bus terminal segments. Positioned as the hardware interface layer between the network and independent I/O channels, it executes real-time protocol conversion, galvanic isolation, distributed data packet polling, and sub-millisecond bus synchronization.
Standard PROFIBUS DP Protocol Integration
Physical Galvanic Isolation Protection Topology
Bidirectional Bus Conversion Drive
The BK3120 Bus Coupler delivers high data throughput efficiency within distributed network topologies, utilizing internal data buffers to convert complex cyclic PROFIBUS DP telegrams into high-frequency local serial K-Bus sequences. Within multi-station network architectures, this module supports the direct connection of up to 32 nodes without repeaters, and can expand up to 125 nodes via fieldbus segmentation techniques.
Its underlying telegram processing mechanism automatically filters out redundant burst interference from the network, unpacking and mapping only valid process data locally, which guarantees high linearity in analog sampling and strict synchronization in digital triggering while eliminating the risk of data congestion and telegram drops in large-scale distributed control loops.
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description.
BECKHOFF BK3120 Bus Coupler Manuals, Datasheets, Drivers, Link
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description.
Automotive Manufacturing
Collects proximity sensor signals and controls pneumatic valve manifolds on automated welding and assembly conveyor lines.
Plastic & Rubber Processing
Connects thermocouple inputs and analog linear position transducers on multi-zone plastic injection molding machines.
Iron & Steel Metallurgy
Collects hydraulic pressure transducer data and controls auxiliary cooling solenoid valves in continuous casting sections.
Mining & Material Handling
Monitors belt misalignment switches and controls lubrication pump starters on long-distance overland conveyor systems.
Printing & Paper Converting
Monitors tension control load cells and controls web guiding actuators on high-speed rotary printing presses.
Water & Wastewater Treatment
Gathers 4-20mA analog signals from ultrasonic level transmitters and transmits control commands to chemical dosing pumps.
When operating the BK3120 Bus Coupler, hot-swapping, dissolving terminal segments, or wiring under power is strictly prohibited. The 24 VDC system supply and peripheral power must be completely isolated to prevent electric arcing or surges from damaging internal circuitry.
The total K-Bus current consumption of all attached downstream I/O modules must not exceed 500 mA, an extension power supply module must be integrated if this limit is exceeded. When positioned as a terminal node in the PROFIBUS network, the termination resistor switch on the D-sub connector must be set to "ON". The node address must be configured via the rotary switches prior to powering up and remain unique across the network. any changes made during runtime require a power cycle to take effect.
Alternative Names
BK312OBK3I20BK3I2O
Technical notes
Hot-swapping or live wiring is strictly prohibited for the 990-10-XX-01-00 163930-01. Ensure a stable loop supply of +12 to +35 VDC. As a 163930-01 special modification, it must be strictly matched with the original 3300 NSv probe and designated cable length, do not mix components. Keep external terminals dry to prevent signal drift .
The Beckhoff BK3120 is an industrial PROFIBUS DP Bus Coupler designed to link modular I/O expansion terminals to a central control network.
What is the primary function of Beckhoff BK3120?
Its primary function is to act as a gateway that links local I/O Bus Terminals to a central PLC or master controller via the PROFIBUS fieldbus protocol.
How do you use the Beckhoff BK3120 Bus Coupler?
It is used by snapping it onto a standard 35 mm DIN rail, attaching I/O Bus Terminals to its right side, connecting the 24 Vdc power supply, and plugging in the PROFIBUS fieldbus cable.
What fieldbus protocol does Beckhoff BK3120 support?
It strictly supports the PROFIBUS DP (Decentralized Periphery) protocol, complying with the international IEC 61158 standard.
How do you set the network address on Beckhoff BK3120?
The PROFIBUS station address is set manually using the hardware rotary switches located on the front panel of the device.
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