Description
Product Introduction
The Bosch Rexroth Indramat DLF1 (primarily encountered as the DLF1.1 series) is a plug-in digital line filter module designed for legacy Indramat motion control system racks. Installed directly into controller backplanes, it provides crucial high-frequency noise filtering and transient voltage suppression for sensitive control logic, encoder signals, and command bus lines.
In heavy industrial automation setups, un-filtered control signals are susceptible to electromagnetic interference (EMI) generated by nearby high-power pulse-width modulated (PWM) drives and switching power supplies. The DLF1 conditions incoming and outgoing digital communication pathways, preventing signal jitter, false pulse registration, and communication time-outs across drive racks.
Key Technical Specifications
| Parameter | Value / Description |
| Manufacturer | Bosch Rexroth / Indramat |
| Model Code | DLF1.1 (e.g., DLF1.1-1-M1-M) |
| Product Type | Digital Line Filter / Signal Attenuator Card |
| Form Factor | European Standard Eurocard / Rack-Mount Slot Module |
| Bus Interface | Edge Connector to Indramat Controller Backplane |
| Function | EMI / RFI Noise Suppression for Control Signals |
| Cooling | Passive Air Convection within Drive Rack |
| Operating Temp | 0°C to +55°C (32°F to 131°F) |
Application Scenarios & The “Trench” Experience
A CNC transfer line loses axis positioning synchronization whenever a nearby heavy induction motor starts up. Diagnostic logs show erratic pulse counts on the feedback bus due to high-frequency noise bleeding into un-filtered signal lines.
- Automotive Stamping & Robotics – Filters noise from high-current welding transformers away from controller backplane buses.
- Precision CNC Machining Racks – Cleanly conditions positioning signals between NC control units and drive amplifiers.
- Printing & Converting Equipment – Prevents web-registration errors caused by static discharge and drive switching noise.
- Packaging Machines – Maintains crisp edge detection for high-speed indexing sensors.
Real-World Field Case Study
During a retrofit on a metal-forming press, maintenance technicians noticed intermittent bus communication alarms across the main Indramat drive rack. Oscilloscope traces revealed high-voltage noise spikes riding along the internal signal bus, causing the processor to drop packets.
Rather than replacing the entire rack assembly, the team traced the issue to degraded suppression capacitors on an older filter card. Inserting a bench-tested Indramat DLF1.1 filter module into the designated rack slot immediately dampened the high-frequency ringing on the line. The system cleared its bus fault indicators and resumed continuous operation without requiring software re-configuration.
DLF1.1
DLF1.1
Transparency SOP: Quality Assurance & Testing
Every surplus or refurbished Rexroth Indramat DLF1 line filter card undergoes a rigorous multi-step bench verification process prior to shipping:
- Visual & Structural Audit: Inspect printed circuit board (PCB) traces, edge connector gold fingers, front faceplate hardware, and filter capacitors for cracks, burns, or cold solder joints.
- Backplane Insertion & Pin Continuity: Test the card inside a standard Indramat rack chassis to verify secure seating, mechanical alignment, and firm pin contact.
- Signal Pass-Through & Attenuation Test: Feed multi-frequency test signals and induced noise patterns through the module channels to confirm specified filtering performance and signal integrity.
- Thermal Stress Test: Run the card under normal logic bus load inside a temperature-controlled chamber to ensure stability across operating temperatures.
- Anti-Static Packaging: Clean connector contacts and seal the module inside heavy-duty static-shielding bags with custom protective foam padding.
The Veteran’s Tech Trap Guide (Crucial Value-Add)
⚠️ Verify Exact Model Code Suffixes: Indramat modules use detailed model codes (such as DLF1.1-1-M1-M). Ensure that hardware version codes match your system schematics to guarantee correct pinout mapping and filtering characteristics.
❗ Power Down Before Insertion/Removal: Never plug or unplug the DLF1 card while the rack backplane is energized! Hot-swapping card-edge modules can arc across connector pins and damage onboard filter arrays or neighboring processor boards.
⚠️ Inspect Rack Guide Rails: Inspect the card slot guide rails for dust, metal shavings, or bent pins before inserting the card. Debris inside the backplane receptacle can short out connector pins upon power-up.
❗ Check Grounding Continuity: The line filter relies on a clean, low-impedance connection to the rack earth ground. Ensure the rack chassis is properly bonded to main plant earth; otherwise, filtered noise will have no discharge path.
Frequently Asked Questions (FAQ)
Q: Is the Indramat DLF1 card hot-swappable?
A: No. Always disconnect 24VDC control power and main line voltage to the system rack before inserting or removing the DLF1 card.
Q: Does the DLF1 require software parameter setup?
A: No. The DLF1 is a purely hardware-level signal filtering board. It operates passively/actively on the electrical layer and requires no software parameterization or firmware downloads.
Q: What is the main sign that a line filter card like the DLF1 has failed?
A: Common symptoms include unexplained bus communication errors, erratic encoder positioning feedback, or high susceptibility to electrical noise whenever nearby heavy machinery turns on.
Q: What is the difference between a main AC power line filter and the DLF1?
A: An AC power line filter conditions high-voltage 3-phase mains electricity (e.g., 230V/480V) entering a drive. The DLF1 is a specialized signal-level filter card designed to clean up low-voltage digital control signals inside the controller rack.
Q: What warranty is offered on surplus DLF1 modules?
A: All tested surplus and refurbished Indramat DLF1 line filter modules supplied through our channels come backed by a full 12-month operational replacement warranty.
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