Beckhoff BK3120 – PROFIBUS DP Bus Coupler Power Module | BK Series Fieldbus Platform
Engineering Background: The BK3120 is Beckhoff’s dedicated PROFIBUS DP bus coupler designed to connect the K-Bus I/O terminal system to PROFIBUS DP networks. Operating as a transparent gateway between the fieldbus and modular I/O, it enables deterministic, high-speed data exchange in distributed control architectures. The BK3120 is widely deployed in machine automation, process control panels, and factory-floor distributed I/O stations where PROFIBUS DP remains the backbone fieldbus protocol.
Product Positioning: Targeted at procurement engineers and system integrators sourcing certified Beckhoff components for PROFIBUS DP installations, the BK3120 delivers plug-and-play compatibility with the full Beckhoff KL/EL terminal range. Konmask.com supplies verified OEM units with full traceability, supporting both new-build projects and legacy system maintenance.
Complete Technical Specifications
- Part Number / SKU: BK3120
- Manufacturer: Beckhoff Automation GmbH & Co. KG
- Product Series: BK Series Bus Couplers
- Fieldbus Protocol: PROFIBUS DP (EN 50170 / IEC 61158)
- PROFIBUS DP Transfer Rate: 9.6 kbaud – 12 Mbaud (auto-detection)
- Max. I/O Terminals: Up to 64 K-Bus terminals per coupler station
- Max. Process Data: 244 bytes input / 244 bytes output
- Power Supply Voltage: 24 V DC (−15% / +20%)
- Current Consumption (K-Bus): Typ. 70 mA
- Power Dissipation: Typ. 1.7 W
- Electrical Isolation: 500 V (fieldbus / supply)
- Operating Temperature: 0 °C … +55 °C
- Storage Temperature: −25 °C … +85 °C
- Protection Class: IP 20
- Mounting: DIN rail (EN 60715, 35 mm)
- Dimensions (W × H × D): 44 mm × 100 mm × 68 mm
- Weight: Approx. 130 g
- Certifications: CE, UL, ATEX (Zone 2), cULus
- PROFIBUS Address Setting: Rotary switch (0–99) + software-configurable
- Diagnostic LED Indicators: Power, Run, I/O Error, Bus Error
Proven Application Environments
- Distributed I/O stations on PROFIBUS DP networks in automotive assembly lines
- Machine tool control panels integrating Siemens SIMATIC S7 / S5 PLC masters
- Packaging machinery with high-speed cyclic I/O polling requirements
- Water treatment and utilities SCADA systems with remote I/O clusters
- Building automation and HVAC control panels requiring modular expansion
- Legacy PROFIBUS DP retrofit projects requiring certified coupler replacements
Engineering Advantages
- Auto Baud Rate Detection: Eliminates manual configuration; coupler self-adapts to master baud rate from 9.6 kbaud to 12 Mbaud.
- K-Bus Compatibility: Seamlessly integrates with the full Beckhoff KL analog, digital, and specialty terminal range without additional gateways.
- Compact DIN-Rail Form Factor: 44 mm width minimizes panel footprint in space-constrained enclosures.
- Robust Electrical Isolation: 500 V isolation between fieldbus and supply protects against ground loops and transient surges.
- Diagnostic Transparency: Onboard LED matrix provides real-time bus status, I/O error, and power fault indication without requiring a programming device.
- GSD File Support: Standard PROFIBUS GSD file available for seamless integration into any PROFIBUS DP master configuration tool (STEP 7, TIA Portal, etc.).
System Architecture & Signal Flow
The BK3120 connects to the PROFIBUS DP master via a 9-pin D-Sub connector (RS-485). On the right side, K-Bus terminals are snapped onto the DIN rail in sequence. The coupler maps terminal process data cyclically into the PROFIBUS DP data frame. Input data from field devices (sensors, encoders) is transmitted upstream to the PLC master; output data (actuator commands) is distributed downstream to the respective output terminals. The internal K-Bus operates at 12 Mbaud independently of the PROFIBUS DP baud rate, ensuring minimal latency across the terminal chain.
Sourcing & Quality Verification
- Origin: Genuine Beckhoff OEM units sourced through authorized distribution channels
- Inspection: Each unit undergoes visual inspection, label verification, and functional power-on check prior to shipment
- Traceability: Serial number and date code recorded; documentation available on request
- Packaging: Original Beckhoff anti-static packaging retained where available; ESD-safe repackaging applied otherwise
- Warranty: 12-month Konmask quality guarantee against manufacturing defects
Procurement Process
- Confirm Requirement: Verify BK3120 against your PROFIBUS DP master GSD configuration and K-Bus terminal list.
- Request Quote: Contact support@konmask.com with quantity, delivery timeline, and destination country for a formal quotation.
- Order Placement: Purchase order accepted via email or online checkout. Proforma invoice issued for wire transfer or credit card payment.
- Lead Time: In-stock units ship within 1–3 business days. ETA provided at order confirmation.
- Shipping: DHL Express / FedEx International with full tracking. Export documentation (commercial invoice, packing list, COO) included.
- After-Sales: Technical support available via email for integration queries within 30 days of delivery.
Technical FAQ
Q: Is the BK3120 compatible with PROFIBUS DP-V1 and DP-V2 masters?
A: The BK3120 supports PROFIBUS DP-V0 and DP-V1 services. DP-V2 isochronous mode is not supported. Verify master compatibility via the GSD file before commissioning.
Q: How many K-Bus terminals can be connected to one BK3120?
A: Up to 64 K-Bus terminals per coupler station, subject to the 244-byte process data limit per direction.
Q: Can the BK3120 replace a BK3100 or BK3110 in an existing installation?
A: Yes, the BK3120 is pin-compatible and functionally equivalent to earlier BK31xx variants. Re-import the GSD file and re-configure the PROFIBUS address if required.
Q: What is the maximum cable length for PROFIBUS DP at 12 Mbaud?
A: Per EN 50170, maximum segment length at 12 Mbaud is 100 m. Use PROFIBUS-certified cable (Type A) and proper termination resistors at both ends of each segment.
Q: Does Konmask provide the Beckhoff GSD file for the BK3120?
A: Yes. The GSD file is available for download upon request. Contact support@konmask.com.
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