Inovance SV660A Series High-Performance Servo Drive User Guide: Operation Panel, Position Control, Electronic Gear Ratio and Fault Troubleshooting
Introduction to the SV660A Series
The Inovance SV660A series is a high-performance, small-to-medium power AC servo drive developed by Inovance Technology. Designed for precision motion control applications, the SV660A covers a power range from 0.05 kW to 7.5 kW and is specifically engineered to support CANlink communication protocol. This differentiates it from the SV660P series, which supports Modbus, CANopen, and CANlink protocols. By focusing exclusively on CANlink, the SV660A provides a streamlined, cost-effective solution for multi-axis networking applications where Inovance’s proprietary bus protocol is the preferred communication standard.
The SV660A is paired with the MS1 series high-response servo motors, which are available in both small-inertia and medium-inertia configurations. These motors feature 23-bit single-turn absolute encoders or 23-bit multi-turn absolute encoders, delivering a resolution of 8,388,608 pulses per revolution. This exceptionally high encoder resolution ensures precise positioning, smooth rotation, and quiet operation, making the SV660A ideal for electronics manufacturing, robotic arms, packaging machinery, and CNC machine tools.
The drive incorporates adaptive rigidity table settings, inertia identification, and vibration suppression functions, simplifying the commissioning process while maintaining high dynamic performance. This article provides a comprehensive guide covering the operation panel, control modes, CN1 terminal wiring, electronic gear ratio calculation, and fault troubleshooting specific to the SV660A series.
Operation Panel and Status Display
The SV660A servo drive is equipped with a 5-digit, 8-segment LED display that serves as the primary interface for monitoring drive status and configuring parameters. The operation panel consists of five keys that enable full parameter navigation and modification without requiring an external computer.
Panel Keys and Their Functions
The operation panel features the following five keys, each dedicated to a specific navigation and editing function:
| Key | Function |
|---|---|
| MODE | Cycles through function code groups sequentially |
| UP (triangle) | Increases the value of the currently blinking digit |
| DOWN (triangle) | Decreases the value of the currently blinking digit |
| LEFT SHIFT (double arrow) | Moves the blinking cursor one position to the left; long press enables page turning when values exceed 5 digits |
| SET | Saves the modified value and enters the next-level menu |
Status Display Modes
Upon power-up, the LED display shows the current servo status. Users can cycle through different monitoring screens using the MODE key. The drive supports several display states, including motor speed (rpm), position command counter, torque command, average load rate, and bus voltage. When a fault or warning occurs, the display automatically switches to show the alarm code (such as Er.620 for motor overload) along with a sub-code that provides additional diagnostic detail.
The panel also supports external I/O status display, allowing users to verify the ON/OFF state of digital input and output signals in real time. This feature is particularly useful during commissioning to confirm that all wiring connections are correct before enabling the motor.
Alarm History and Forced Output
The SV660A records the most recent 10 alarm events, which can be reviewed through the panel for diagnostic purposes. Additionally, the drive supports a forced output function that enables users to manually activate output signals regardless of the servo’s actual status. This is invaluable for verifying wiring connections on digital output terminals during initial setup.
Position, Speed, and Torque Control Modes
The SV660A supports three primary control modes, each suited to different application requirements. The control mode is selected through parameter H02.00, and the drive can also operate in a mixed control mode where the active mode is determined by the state of designated digital input signals.
Position Control Mode
Position control is the most commonly used mode in servo applications. The SV660A receives position commands via pulse trains from an upper-level controller (such as a PLC or motion controller). The total number of pulses determines the target position, while the pulse frequency determines the motor speed. The drive closes the position loop internally using feedback from the 23-bit absolute encoder, ensuring precise positioning accuracy.
The position control loop includes a position command filter that processes the signal after electronic gear ratio conversion, smoothing the command trajectory and reducing mechanical shock. A position ramp function is also available, enabling gradual acceleration in response to position commands for applications requiring smooth motion profiles.
Speed Control Mode
In speed control mode, the motor speed is regulated by a speed command provided through CANlink communication. The drive’s internal speed loop achieves fast and accurate speed regulation, making this mode suitable for applications where the upper-level controller closes the position loop externally. Typical applications include CNC milling machines and grinding equipment where the host controller manages positioning while the servo drive handles speed regulation.
Torque Control Mode
Torque control mode regulates the motor’s output torque rather than its position or speed. Since the motor current is linearly proportional to torque, the drive achieves torque control by regulating the current loop. Torque commands are provided via CANlink communication. This mode is primarily used in tension control applications such as winding and unwinding systems, where the torque setpoint must remain constant regardless of changes in the winding radius.
CN1 Terminal Wiring and Pulse Input
The CN1 connector on the SV660A serves as the primary interface for command input signals and digital I/O. Proper wiring of this connector is critical for reliable servo operation. The CN1 terminal provides connections for pulse command inputs, digital inputs (DI), digital outputs (DO), and analog outputs (AO).
Pulse Input Configuration
The SV660A supports four types of pulse train input formats, selectable through parameter H05.00:
| Setting | Pulse Input Format | Description |
|---|---|---|
| 0 | Pulse + Direction | CW pulse with direction signal |
| 1 | CW/CCW Pulse | Separate forward and reverse pulse inputs |
| 2 | AB Phase Quadrature | 90-degree phase-shifted A/B signals |
| 3 | AB Phase Quadrature (4x) | 4x multiplication of quadrature signals |
The maximum pulse input frequency depends on the voltage level of the input signal. For 5V differential pulse inputs, the drive supports frequencies up to 4 MHz. For 24V open-collector inputs, the maximum frequency is lower due to the inherent limitations of the input circuit. The pulse input wiring must use twisted-pair shielded cables to minimize electromagnetic interference, especially when operating at high pulse frequencies.
Digital Input and Output Terminals
The CN1 connector provides multiple digital input (DI) terminals that can be assigned to various functions through the H03 parameter group. Available DI functions include servo enable (S-ON), forward/reverse rotation inhibition, fault reset (ALM-RST), origin return start, electronic gear ratio selection, and emergency stop. Each DI terminal can be independently configured for normally open or normally closed logic.
Digital output (DO) terminals are configurable through the H04 parameter group. Common DO functions include servo ready, alarm output, positioning completion, zero speed detection, and brake control. When driving inductive loads such as relay coils from DO terminals, absorption diodes must be installed across the relay coil to protect the output circuit from voltage spikes.
Encoder Output Signal
The SV660A provides encoder signal output through the CN1 connector, allowing the upper-level controller to receive position feedback. The output can be configured as a divided pulse output with the division ratio set through parameter H05.17. The division ratio must not exceed the encoder resolution; for the 23-bit encoder with 8,388,608 pulses per revolution, the divided pulse output setting must remain within this limit.
Electronic Gear Ratio Calculation
The electronic gear ratio is a fundamental concept in position control servo systems. It establishes the proportional relationship between the input pulse command (in instruction units) and the motor movement (in encoder units). The SV660A supports two groups of electronic gear ratios, which can be switched during operation via a designated DI signal.
Gear Ratio Parameters
The electronic gear ratio is defined by the following parameters:
| Parameter | Name | Range | Default |
|---|---|---|---|
| H05.09 | Gear ratio numerator (Group 1) | 1 to 4,294,967,295 | 1 |
| H05.10 | Gear ratio denominator (Group 1) | 1 to 4,294,967,295 | 1 |
| H05.11 | Gear ratio numerator (Group 2) | 1 to 4,294,967,295 | 1 |
| H05.12 | Gear ratio denominator (Group 2) | 1 to 4,294,967,295 | 1 |
The gear ratio can be expressed as: Motor displacement = Load axis displacement x Gear ratio, where the gear ratio equals the numerator divided by the denominator. The allowable range for the gear ratio is from 0.001 times the encoder resolution divided by 10,000 to 4,000 times the encoder resolution divided by 10,000. Exceeding this range will trigger fault Er.B03 (electronic gear setting exceeded limit).
Calculation Example: Ball Screw Application
Consider a ball screw system with the following specifications:
- Command minimum unit: 1 mm (0.001 m)
- Ball screw lead: 10 mm per revolution
- Reduction ratio: 5:1 (motor rotates 5 times for one screw revolution)
- 23-bit encoder resolution: 8,388,608 pulses per revolution
The calculation proceeds as follows:
For every 1 mm of linear movement, the screw rotates 1/10 of a revolution. With a 5:1 reduction ratio, the motor rotates 5 x (1/10) = 0.5 revolutions per millimeter of linear travel. The corresponding encoder pulses are 0.5 x 8,388,608 = 4,194,304 pulses per millimeter.
Therefore, the gear ratio numerator should be set to 4,194,304 and the denominator to 1. This means that when the upper-level controller sends 1 pulse (representing 1 mm of movement), the servo drive internally moves the motor by 4,194,304 encoder pulses, achieving the desired linear positioning.
It is essential to mathematically reduce the numerator and denominator to their simplest form (removing common factors) before entering the values into the drive parameters. This ensures optimal computation accuracy within the drive’s FPGA.
CANlink Communication and CiA402 State Machine
CANlink Protocol Overview
The SV660A utilizes Inovance’s proprietary CANlink communication protocol as its sole fieldbus interface, distinguishing it from the SV660P which additionally supports Modbus and CANopen. CANlink operates on the CAN physical layer with a maximum baud rate of 1 Mbps and supports up to 16 nodes on a single bus. The protocol uses a master-slave architecture where the master controller (typically an Inovance PLC or motion controller) polls each servo drive for status data and sends command data in cyclic frames. The CANlink node address is set through parameter H0C.00, and the baud rate is configured through H0C.01. Each node must have a unique address; duplicate addresses will trigger Er.994 (CAN address conflict).
CANlink communication supports two data transfer modes: cyclic data exchange for real-time control of position, speed, and torque commands, and acyclic parameter access for reading and writing drive parameters during commissioning. The cyclic data exchange uses a fixed-length data frame structure defined by the configuration parameters in the H0C group, ensuring deterministic communication timing. For multi-axis applications, the CANlink bus provides a cost-effective alternative to EtherCAT while still delivering sufficient real-time performance for most general-purpose automation tasks.
CiA402 State Machine Integration
Despite using CANlink rather than CANopen, the SV660A implements the CiA402 drive profile state machine, which is the industry-standard state transition model for servo drives. The state machine governs the drive’s operational states and the transitions between them, ensuring orderly startup, configuration, and operation. The six primary states are: “Not Ready to Switch On,” “Switch On Disabled,” “Ready to Switch On,” “Switched On,” “Operation Enable,” and “Quick Stop Active.” Each transition is triggered by control word bits from the master controller or by internal drive conditions such as fault detection.
The control word (corresponding to object 6040h in the CiA402 profile) and status word (6041h) are mapped to CANlink cyclic data frames, allowing the master controller to manage the state machine transitions. To enable the servo for operation, the master must sequence the control word through the standard “Shutdown” to “Switch On” to “Enable Operation” transitions. This ensures that the drive is properly configured and all safety conditions are met before motor power is applied.
Fault Codes and Troubleshooting
The SV660A classifies alarms into two categories: faults (Er.xxx) and warnings (Er.xxx). Faults cause the servo to stop and cut off motor power, while warnings alert the operator without necessarily stopping operation. The following table summarizes the most commonly encountered fault codes and their meanings:
Common Fault Codes
| Fault Code | Description | Primary Cause |
|---|---|---|
| Er.101 | Servo internal parameter abnormality | Internal parameter corruption or EEPROM failure |
| Er.102 | Programmable logic configuration fault | Drive hardware damage or software version mismatch |
| Er.108 | Parameter storage fault | EEPROM read/write failure |
| Er.120 | Product matching fault | Motor and drive power mismatch or incorrect motor ID |
| Er.130 | DI function duplicate assignment | Same DI function assigned to multiple terminals |
| Er.201 | Overcurrent (hardware) | Output short circuit or ground fault |
| Er.210 | Output ground short circuit | Motor cable shorted to ground |
| Er.220 | Phase sequence error | U/V/W wiring incorrect |
| Er.234 | Runaway (flying) | Feedback signal loss or severe disturbance |
| Er.400 | Main circuit overvoltage | Bus voltage exceeds threshold during deceleration |
| Er.410 | Main circuit undervoltage | Input voltage below specification |
| Er.420 | Power phase loss | Three-phase input missing one phase |
| Er.500 | Overspeed | Motor speed exceeds allowable maximum |
| Er.610 | Drive overload | Average load rate exceeding 80% for extended period |
| Er.620 | Motor overload | Motor thermal accumulation exceeds threshold |
| Er.630 | Stall motor overheat protection | Motor stalled with high current causing overheating |
| Er.650 | Heatsink overheat | Drive heatsink temperature exceeds 90-95 degrees C |
| Er.731 | Encoder battery failure | Absolute encoder battery voltage below 3.0V or depleted |
| Er.740 | Encoder communication abnormality | Encoder cable interference or disconnection |
| Er.950 | Forward overtravel warning | Positive travel limit switch activated |
| Er.952 | Reverse overtravel warning | Negative travel limit switch activated |
| Er.990 | Input phase loss warning | Single-phase input detected on three-phase drive |
| Er.994 | CAN address conflict | Duplicate CANlink node addresses on the bus |
Troubleshooting Key Faults
Er.610 Drive Overload: This fault occurs when the drive’s average load rate (monitorable through H0b.12) consistently exceeds 80%. The primary causes include excessive load inertia, mechanical jamming, or insufficient drive capacity. To diagnose, perform inertia identification by setting H0D-02 to 1 and pressing the UP or DOWN key to rotate the motor. The identified inertia ratio is stored in H08.15. If the inertia ratio exceeds 120 times, a larger drive or mechanical redesign is necessary.
Er.630 Stall Motor Overheat: This protection activates when the motor is stalled under load, causing excessive current and temperature rise. The detection time threshold is set through H0A.32. To troubleshoot, first check whether the motor is mechanically locked by disconnecting the load and manually rotating the motor shaft. Verify the U/V/W power cable connections for continuity and correct phase sequence. If the motor power cable is disconnected or has a broken wire, the drive cannot properly commutate the motor, leading to stall conditions.
Er.731 Encoder Battery Failure: This fault occurs when the absolute encoder battery voltage drops below 3.0V or when the battery is first installed. When first connecting the battery, Er.731 will appear; set H0d.20 to 1 to reset the encoder fault and initialize the absolute position system. If the battery voltage drops below 3.0V during operation, Er.730 (encoder battery warning) will be triggered first, providing advance notice to replace the battery before data loss occurs. The replacement battery should be a 3.6V lithium battery matching the drive’s specifications.
Er.234 Runaway (Flying): This fault indicates that the motor speed has deviated significantly from the commanded speed without proper feedback control. Common causes include encoder signal loss due to cable damage, severe electromagnetic interference on the encoder line, or incorrect motor phase sequence (Er.220). In vertical axis applications where gravity assists motor movement, the runaway detection can be disabled through parameter H0A.13 to prevent false alarms during normal gravitational descent.
Er.994 CAN Address Conflict: This fault is specific to CANlink-based systems and occurs when two or more servo drives on the same bus are assigned identical node addresses. To resolve, verify that each drive has a unique CANlink address set through parameter H0C.00, and ensure the total number of nodes does not exceed the bus specification.
Warning Codes and Non-Stop Alarms
In addition to fault codes that stop the motor, the SV660A generates warning codes that alert the operator to conditions that require attention but do not immediately halt operation. Understanding these warnings enables proactive maintenance:
| Warning Code | Description | Action Required |
|---|---|---|
| Er.730 | Encoder battery low voltage | Replace battery before voltage drops below critical level |
| Er.900 | DI emergency stop activated | Check emergency stop circuit and clear the DI signal |
| Er.909 | Motor overload warning | Reduce load or increase acceleration/deceleration time |
| Er.920 | Brake resistor overload | Check brake resistor wiring and capacity |
| Er.941 | Parameter change requires power cycle | Power cycle the drive to activate changed parameters |
| Er.942 | Frequent parameter storage | Reduce frequency of parameter writes via communication |
Conclusion
The Inovance SV660A series servo drive provides a robust and precise motion control solution for CANlink-based automation systems. Its 23-bit absolute encoder delivers exceptional positioning accuracy, while the comprehensive operation panel enables efficient on-site configuration without external tools. The electronic gear ratio system allows flexible adaptation to various mechanical transmission configurations, and the extensive fault and warning code system enables rapid diagnosis and resolution of operational issues.
By understanding the operation panel functions, correctly wiring the CN1 terminals, properly calculating the electronic gear ratio, and familiarizing oneself with the fault code table, engineers can effectively deploy and maintain the SV660A in diverse industrial applications. The drive’s adaptive tuning features, including automatic rigidity adjustment and vibration suppression, further simplify commissioning and ensure stable, high-performance operation throughout the equipment lifecycle.