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1. Introduction

In modern CNC and industrial automation systems, DRIVE-CLiQ (Drive Component Link with IQ) serves as the critical communication backbone connecting various drive components in SINAMICS systems. When alarm 231885 appears on your control panel displaying “Encoder 1 DRIVE-CLiQ (CU): Cyclic data transfer error,” it indicates a serious communication interruption that requires immediate attention. This technical blog provides maintenance personnel with detailed insights into understanding, diagnosing, and resolving this alarm effectively.

2. Root Causes of Alarm 231885

Alarm 231885 is triggered when a DRIVE-CLiQ communication error occurs between the Sensor Module (encoder 1) and the Control Unit, where the nodes fail to send and receive data in proper synchronization. The fault value typically appears in hexadecimal format (0000yyxx hex), where ‘yy’ represents the component number and ‘xx’ indicates the specific error cause.

Cause of failure:

26 (= 1A hex):

The bit indicating connection in the received telegram is not set, resulting in the telegram being received too soon.

33 (= 21 hex):

The cyclic data message was not arrived.

34 (= 22 hex):

The interval in the telegram reception list.

64 (= 40 hex):

Telegram mailing list interval.

98(= 62 hex):

Error during the transition to cyclic operation.

Note regarding the message value:

2.1 Primary Triggering Factors

Communication Synchronization Failure: The most common cause involves asynchronous data transmission between the encoder module and the Control Unit. The cyclic data exchange operates on strict timing requirements, and any deviation leads to immediate alarm generation.

Physical Connection Issues: Loose, damaged, or improperly terminated DRIVE-CLiQ cables represent a significant percentage of alarm occurrences. The specialized DRIVE-CLiQ cables require proper shielding and secure connections at both ends.

Electromagnetic Interference (EMI): Poor cabinet design, inadequate cable routing, or proximity to high-power motor cables can induce electromagnetic interference that corrupts the cyclic data transmission. DRIVE-CLiQ operates at high frequencies and is susceptible to EMI when shielding is compromised.

Hardware Degradation: Over time, encoder components, sensor modules, or cable connectors can develop internal faults that interrupt cyclic communication. Environmental factors such as temperature extremes, vibration, or contamination accelerate this degradation.

Accumulation of cutting oil Fumes inside the SMI: Cutting oil fumes often accumulate inside the SMI unit of spindle motor ,causing interference in the communication between the encoder and the Siemens controller.

Firmware Incompatibility: Mismatched firmware versions between the Control Unit and DRIVE-CLiQ components can cause communication protocol errors, resulting in cyclic data transfer failures.

Topology Configuration Errors: Incorrect DRIVE-CLiQ topology setup, exceeding component capacity, or violating topology rules can overload the communication network and trigger cyclic data errors.

3. Impact and Consequences of Alarm 231885

3.1 Immediate System Effects

When alarm 231885 activates, the system typically initiates an ENCODER fault response, which may include immediate axis control stoppage (IASC) or dynamic braking (DCBRK). The affected axis loses position feedback, making continued operation unsafe and impossible. The alarm requires immediate acknowledgment and cannot be cleared until the underlying issue is resolved.

3.2 Operational Consequences

Production Downtime: Machine operations halt immediately, resulting in production losses and schedule disruptions. The affected axis cannot execute motion commands without valid encoder feedback.

Position Loss: The servo system loses accurate position information, potentially requiring re-referencing or homing procedures after alarm resolution. In multi-axis systems, this can affect overall machine calibration.

Cascading Alarms: A single DRIVE-CLiQ communication error often triggers secondary alarms such as drive faults (alarm 25201), monitoring clock cycle errors (alarm 201652), or motor temperature sensor faults due to communication loss.

Data Integrity Risks: Prolonged or repeated occurrences may indicate deteriorating hardware that could lead to unpredictable behavior or data corruption in position control systems.

4. Step-by-Step Troubleshooting Procedure

4.1 Safety Precautions (Perform First)

Before beginning any diagnostic work, ensure complete electrical isolation following the six-step safety protocol.

1. Notify all personnel affected by the shutdown procedure
2. Isolate the drive system from all power sources
3. Wait for the complete discharge time indicated on warning labels (typically 5-10 minutes)
4. Verify zero voltage between all power connections using appropriate test equipment
5. De-energize all auxiliary supply circuits
6. Lock out the system to prevent accidental re-energization

4.2 Initial Diagnostics

Step 1: Document Alarm Information
Record the complete alarm message including fault value (r0949 or r2124), component number, and error cause code. This hexadecimal information is critical for root cause analysis.

Step 2: Perform Visual Inspection
Examine all DRIVE-CLiQ cable connections between the Control Unit and encoder sensor module. Look for physical damage, loose connections, bent pins, or contamination at connector interfaces.

Step 3: Check Cable Routing and EMC Compliance
Verify that DRIVE-CLiQ cables are properly separated from power cables and motor lines. Ensure minimum separation distance of 200mm from high-voltage conductors. Confirm proper shield connections at both cable ends.

Step 4: Inspect Encoder Hardware
Check the encoder housing for physical damage, contamination on the scale (for linear encoders), or signs of moisture ingress. Verify that the encoder LED indicators show normal operation patterns.

4.3 Advanced Troubleshooting (Must be perform by Siemens Authorized persons only)

Step 5: Verify DRIVE-CLiQ Topology
Using STARTER or TIA Portal, review the configured DRIVE-CLiQ topology against the actual physical setup. Check parameter p9916 (DRIVE-CLiQ data transfer error shutdown threshold slave) to verify appropriate threshold settings.

Step 6: Perform POWER ON Reset
Execute a complete POWER ON cycle of the affected DRIVE-CLiQ component. This clears temporary communication errors and reinitializes the component handshake sequence.

Step 7: Firmware Verification and Update
Access the “Version Overview” page in your commissioning software to check firmware compatibility between the Control Unit and all DRIVE-CLiQ components. Update if mismatches are detected.

Step 8: Cable Substitution Test
Replace the suspected DRIVE-CLiQ cable with a known-good, certified cable of appropriate length. Non-certified connectors can cause short circuits and module damage.

Step 9: Component Isolation Testing
If the alarm persists, systematically isolate encoder components by temporarily disconnecting other DRIVE-CLiQ devices to identify if network overload or component conflicts exist.

4.4 Resolution Actions

For Cable/Connection Issues: Replace damaged cables with properly specified DRIVE-CLiQ cables featuring adequate shielding (minimum Cat.5e with copper shielding braid). Ensure connector torque specifications are met.

For EMI-Related Problems: Reroute cables according to EMC guidelines, install additional cable shielding, or use ferrite cores at critical connection points.

For Hardware Failures: Replace the defective encoder or sensor module following proper ESD handling procedures. Ensure replacement components match original specifications and firmware versions.

For Topology Issues: Reconfigure the DRIVE-CLiQ network to comply with topology rules, reduce network load, or optimize sampling times (p4643).

5. Essential Safety Precautions for Maintenance Personnel

5.1 Electrical Safety

High Voltage Awareness: Even after power disconnection, capacitors in drive modules may retain hazardous voltages exceeding 300V for several minutes. Always verify zero voltage before touching any components.

Proper Grounding: Ensure all personnel are properly grounded when working on drive systems. Use ESD wrist straps connected to verified ground points.

5.2 ESD Protection Protocols

DRIVE-CLiQ components contain sensitive electronics vulnerable to electrostatic discharge. Mandatory precautions include

• Wear ESD wrist straps or ESD shoes with conductive flooring
• Use ESD-safe work surfaces and packaging materials
• Avoid contact with component circuit boards; handle only edges or designated areas
• Keep components away from monitors and display screens (minimum 10cm distance)
• Never place components on plastic surfaces or near synthetic fabrics

5.3 Mechanical Hazards

Unexpected Motor Movement: Before working on encoder systems, mechanically lock all axes to prevent inadvertent motion. Verify that all energy sources (pneumatic, hydraulic, compressed air) are safely discharged.

Temperature Hazards: Motor surfaces can exceed 80°C during operation. Allow adequate cooling time before handling encoder assemblies.

5.4 Documentation and Verification

• Back up all parameter sets and system configuration before making changes
• Maintain detailed maintenance logs documenting alarm history, actions taken, and results
• Verify proper system operation through test cycles before returning to production
• Perform encoder adjustment procedures using motion-based techniques when replacing components

6. Conclusion

Alarm 231885 represents a critical DRIVE-CLiQ communication fault requiring systematic diagnosis and resolution. By understanding the root causes—ranging from physical cable issues to firmware incompatibility—maintenance personnel can efficiently restore system operation. The troubleshooting procedure emphasizes safety-first protocols, methodical investigation, and proper component handling. Regular preventive maintenance, including periodic inspection of DRIVE-CLiQ connections, proper cable routing verification, and firmware updates, significantly reduces the occurrence of this alarm and ensures reliable long-term system performance.

Disclaimer: The blogs shared on CNC machines are created purely for *educational purposes*. Their intent is to help readers understand CNC controls, alarms, diagnostics, and general troubleshooting methods. We strictly avoid any copyright violations, and all explanations are written only for learning and knowledge-sharing.  These blogs should not be considered as official repair or service manuals. For detailed instructions, critical repairs, or advanced troubleshooting, it is always necessary to contact and work under the guidance of the respective *machine manufacturer* or *CNC controller support team*.  The content provided is focused only on *diagnosis and awareness*. We do not take responsibility for any kind of damage, error, or malfunction that may occur if someone directly applies the information shared here without proper technical supervision