LTI ServoOne Servo Troubleshooting Guide

Troubleshooting of encoder interface and motor feedback faults

ServoOne provides two encoder interfaces (X7 and X8), supporting multiple protocols such as Parser, SinCos, TTL, SSI, EnDat, and HIPERFACE DSL.

1. Hiperface DSL single cable technology

For LSP series servo motors, ServoOne supports Hiperface DSL single cable interface. This technology integrates encoder signals and motor temperature signals into a two-wire cable, greatly simplifying wiring.

Communication failure: If the panel reports "Encoder error" or cannot read motor parameters, first check if the shielding layer of the motor cable (such as KM13 model) is 360 degrees clamped on the grounding clamp of the driver. Secondly, check whether the encoder inside the motor is damaged due to overheating or overvoltage. The Hiperface DSL interface has extremely high requirements for impedance matching, and it is strictly prohibited to splice it randomly on non original cables.

Temperature sensor malfunction: If a "Motor temperature sensor error" is reported, the temperature sensor pins inside the cable need to be checked. If using a third-party motor, it is necessary to confirm whether the KTY or PTC sensor parameters match the ServoOne software configuration.

2. Second encoder and fully closed-loop control

When the X8 interface is configured as the second encoder input (option 2 technology package is required), it is commonly used for full closed-loop control of external grating rulers. If a "Position deviation" alarm occurs, check the signal amplitude of the grating ruler (usually a 1Vs sine wave). Use an oscilloscope to measure channels A/B. If there is amplitude attenuation or phase shift, it indicates that the reading head of the grating ruler is dirty or the cable is damaged. After replacing the grating ruler, it is necessary to perform commutation offset self-learning again.

Specification for replacement of critical hardware and EMC compliance

When replacing key components such as main power filters, reactors, or braking resistors, strict adherence to electromagnetic compatibility (EMC) requirements is necessary, otherwise it may result in equipment failure to pass acceptance or frequent interference with other equipment.

1. Main power filter and reactor

The EMC performance of ServoOne is highly dependent on external main power filters (such as EMC7.1-UR to EMC500.1-UR) and incoming reactors (LR34 series).

Replacement rule: When replacing the filter, it is necessary to choose a product that matches the rated current of the prototype number. For example, for the SO84.045 model, it is usually matched with an EMC63.1-UR filter. The metal casing of the filter must be reliably overlapped with a large area of metal mounting backplate to ensure smooth discharge of high-frequency interference current. If the cable is too long, shielded cable should be used and both ends of the shielding layer should be grounded.

2. Braking Resistors

For single axis systems without regenerative power supply, braking energy is converted into thermal energy consumption through external braking resistors (such as BR-090 or BR-026 series).

Troubleshooting and replacement: If the driver reports a "Brake chopper" fault, after confirming that the internal IGBT has not broken down, the resistance of the external brake resistor needs to be measured. If the resistor breaks due to overheating (infinite resistance), it must be replaced with a resistor of the same specification. Please note that some models (such as SO84.xxx.xxxx.1xxx) have integrated braking resistors internally. It is strictly prohibited to directly connect external resistors in parallel on such models, otherwise it may cause overcurrent and burnout of the chopper.

3. Fan and heat dissipation

ServoOne's fan is a consumable part. When replacing the fan, it is necessary to turn off the power and wait for the DC bus capacitor to discharge completely (the panel indicator light goes out). When installing a new fan, be sure that the wind direction arrow must face towards the outside of the cabinet or comply with the air duct design. For modules with IP20 protection level, the fan grille cannot be removed to prevent foreign objects from entering and causing short circuits.