Pacific Scientific Servo Drive Selection Guide

Pacific Scientific All Digital Servo Drive Series: PC3400, PC800, and SC/SCE900 Technology Selection Guide

In the field of modern industrial automation, the performance, flexibility, and reliability of servo drive systems directly determine the machining accuracy, production efficiency, and long-term operating costs of machines. Pacific Scientific (now a brand under Danaher Motion), as a pioneer in the field of motion control, has long been committed to innovation in fully digital servo drive technology. Its three major series of digital brushless servo drives, PC3400, PC800, and SC/SCE900, cover a wide range of application needs from low power to medium high power, from simple speed control to complex programmable motion control, and from single machine operation to distributed multi axis networking. These drivers all adopt a fully digital closed-loop control architecture based on DSP (Digital Signal Processor), combined with patented DRDC (Digital Rotary Transformer to Digital Converter) technology and Signature sine wave current control, which significantly reduces motor torque ripple and operating noise while eliminating analog drift and improving repeatability accuracy.

This article will provide a detailed technical analysis of these three drive series from the perspectives of product positioning, core technology, power grading, interface functions, tab expansion, supporting motors, and system selection, providing professional selection references for automation engineers and system integrators.

Common technical foundation for all digital servo drives

2.1 Full digital DSP control

PC3400, PC800, and SC/SCE900 all use a single DSP to simultaneously perform digital operations on the current loop, velocity loop, and position loop. The update cycle of the current loop can be as low as 62.5 microseconds, the speed loop is 250 microseconds, and the position loop is 1 millisecond, ensuring extremely high dynamic response capability. All system parameters and application parameters are set through software and stored in EEPROM, completely eliminating the traditional analog potentiometer adjustment and thus eliminating the problems of temperature drift and parameter inconsistency.

2.2 Patent DRDC Rotary Transformer Conversion

These three series all support the use of rotary transformers (Resolvers) as position and velocity feedback components. Pacific Scientific owns the digital rotary transformer to digital converter (DRDC) technology with US patent 5162798, which can directly convert the analog sine/cosine signal of the resolver into 24 bit resolution (approximately 0.0013 arcminutes per revolution) digital position information. The absolute accuracy of the driver itself reaches ± 5.3 arcminutes, and when combined with a typical 20 arcminutes resolver, the overall accuracy is about ± 25 arcminutes. Resolver feedback has the advantages of simple structure, anti vibration, anti oil pollution, and high temperature resistance, making it very suitable for harsh industrial environments.

2.3 Signature Sine Wave Current Control

These three drivers all use patented Signature sine wave current control technology. Unlike traditional trapezoidal wave drive, this technology customizes the "signature" of the output sine wave current based on the waveform characteristics of the motor's back electromotive force, thereby reducing electromagnetic torque ripple to below ± 2%. This enables the motor to achieve extremely smooth operation at all speeds, improving the surface quality and positioning accuracy of machine processing.

2.4 Standard Command Interface

All series come standard with multiple command interfaces:

± 10V analog interface: used for speed or torque control.

Step/direction interface: used for position or speed control, supporting single ended or differential signals.

Pulse addition and subtraction interface: Step Up/Step Down mode.

Orthogonal encoder interface: capable of electronic gear following.

RS-232/RS-485 serial port: used for parameter configuration, debugging, and real-time monitoring.

2.5 Protection and Diagnosis

The driver is equipped with comprehensive protection circuits, including output short-circuit protection (phase to phase, phase to ground), overvoltage/undervoltage protection, over temperature protection (power module and motor PTC input), I ² t current limitation, regenerative overload protection, etc. The fault code is displayed through the multi segment LED on the front panel (PC3400/SC900 is a seven segment digital tube, PC800 is a dual LED), and detailed fault information can be read through the serial port.

PC3400 series: Intelligent all digital servo drive

3.1 Product positioning

The PC3400 series is a new generation of intelligent fully digital servo drives launched by Pacific Scientific, offering both AC powered (PC340xA) and DC powered (PC340xD) versions. It has a complete built-in programmable motion control function, which can independently complete complex motion trajectories, electronic camshafts, and electronic gears without the need for an external motion controller. Specially suitable for applications such as electronic assembly, semiconductor wafer processing, material handling, robots, XY workbenches, and packaging machinery.

3.2 Power level

The PC3400 series covers a continuous power range of 0.21kW to 6.8kW, with a peak power of up to 13.6kW. Specific models include:

Model Continuous current (A rms) Peak current (A rms) Peak time (s) Input power supply

PC3403A 3 6 2 90-253V AC single-phase/three-phase

PC3406A 6 12 2 90-253V AC single-phase/three-phase

PC3410A 10 20 1 90-253V AC single-phase/three-phase

PC3420A 20 40 0.5 90-253V AC single-phase/three-phase

PC3402D 2.5 5 1 20-74V DC

PC3405D 5 10 1 20-74V DC

The driver with AC power supply integrates power supply and brake chopper; The DC version is more compact and suitable for users who already have a DC power supply. The control power supply (24-48V DC) is isolated from the main power supply and can maintain logic power supply when the main power supply is disconnected.

3.3 Key Performance and Functionality

Control algorithm: Advanced Space Vector Modulation algorithm is adopted to improve voltage utilization efficiency.

I/O configuration:

2-channel differential ± 10V analog input (14 bits)

5-channel programmable digital input (4.5-26.5V, optocoupler isolation)

2-channel high-speed digital input (<1 μ s response)

1-channel registration input (<1 μ s)

2-channel programmable digital output (30V/35mA)

1 driver normal/brake relay output (100V/1A)

Encoder simulation output (A, B, Z)

Optional expansion I/O card: adding 16 inputs and 8 outputs.

Programming software: ToolPAC (Windows platform), supports point and click programming, built-in digital oscilloscope function, can graphically display waveforms such as speed, current, position error, etc. Axis Setup Wizard and Tuning Wizard make debugging extremely simple.

Feedback options: Resolver, Hall, Encoder (with Hall or Z-channel commutation), supports dual feedback (main feedback+auxiliary encoder).

Environment and certification: Operating temperature 0-40 ° C, storage -40-70 ° C, humidity 0-95%, no condensation. UL 508C certification (DC version pending), CE compliance.

3.4 Typical Applications

The PC3400 series is particularly suitable for OEM equipment that requires independent motion control and is cost sensitive. For example: SMT machine (high-speed picking and placing), wafer inspection table (high-precision positioning), automatic palletizer (multi-stage speed control), robot joints (smooth acceleration and deceleration).

PC800 series: Compact and cost-effective servo drive

4.1 Product positioning

The PC800 series is a fully digital servo drive designed by Pacific Scientific for small and medium power applications that are cost sensitive and have strict volume requirements. Its volume has been reduced by 40% compared to the previous generation 900 series, but it still maintains DSP full digital control, Resolver feedback, and rich command interfaces. The PC800 driver is equipped with a preset motion contour generator, which can independently complete incremental, absolute, zeroing, and registration movements without the need for an external controller. Meanwhile, the PC840 model supports SERCOS fiber optic networks, making it easy to build distributed multi axis systems.

4.2 Power level

Model Continuous current (A rms) Peak current (A rms) Continuous power (kW) Peak power (kW)

PC8x2 3.75 7.5 1.1 2.25

PC8x3 5.3 10.6 1.5 4.5

PC8x4 10.6 21.2 3.0 9.0

Input power supply: 90-264V AC single-phase or three-phase (240V nominal), built-in power supply and brake chopper. Control logic power supply isolated from main power supply (22-52V DC, optional). Supports forced air cooling at 50 ° C or natural cooling at 40 ° C.

4.3 Key Characteristics

Preset motion: Through an internal contour generator, users can store multiple preset positions and speeds, which can be triggered through I/O selection without programming.

I/O configuration:

6-way optocoupler isolated programmable input (user configurable)

3-channel optocoupler isolated programmable output

1 relay output (30V DC)

Differential ± 10V analog input

Single ended ± 5V analog input

2-channel ± 5V analog output

Encoder simulation output (A, B, Z, resolution up to 16384 PPR)

Encoder input (orthogonal/stepper/directional)

+5V/200mA user output,+24V/100mA auxiliary power supply (for I/O use)

Software tool: PC830 Tools (Windows platform), including digital oscilloscope, automatic tuning, and diagnostic functions.

Feedback: Resolver standard, optional Hall/encoder (for linear motors, etc.).

SERCOS option: The PC840 model integrates SERCON816 ASIC, supporting communication rates up to 16 kHz for real-time distributed control.

Size and Installation: Width only 60mm (PC8x2) to 114mm (PC8x4), depth 218-229mm, weight 3.2-6.6kg. Optional terminal block adapter simplifies wiring.

4.4 Application Scenarios

The PC800 series is particularly suitable for packaging machinery (horizontal and vertical sealing), electronic assembly (small XY table), material handling (conveyor sorting), and multi axis collaborative equipment that requires SERCOS network (such as color group synchronization in printing machines).

SC/SCE900 Series: Modular and Scalable High Performance Servo Drivers

5.1 Product positioning

The SC/SCE900 series is Pacific Scientific's highest end fully digital servo drive platform, featuring a modular design that allows for flexible upgrades from basic serial port configuration to SERCOS fiber optic network and single axis programmable control by inserting different tabs (OC/OE930, 940, 950). The SCE900 model is specifically designed for the European and global markets, with a main power input range of 180-528V AC (three-phase), which can be directly compatible with 400V/480V industrial power grids. It also has a built-in CE filter and does not require an external isolation transformer. The SC900 model is suitable for 240V AC systems.

5.2 Power level

The SC/SCE900 series offers a complete selection from low power to high power:

Model: Continuous Current (A 0-p) Peak Current (A 0-p) Continuous Power (kW) @ 400V Peak Power (kW) @ 400V

SCE9x2 3.75 7.5 1.1 2.2

SC9x3 / SCE9x3 5.3 10.6 2.5 5.0

SC9x4 / SCE9x4 10.6 21.2 5.0 10.0

SC9x5 / SCE9x5 15.9 31.8 7.5 15.0

SCE9x6--18.0 27.0 (estimated)

Note: SCE9x6 is a high-power model (see selection table, specific parameters need to refer to the factory).

SC9xx series input voltage: 180-264V AC three-phase, nominal bus 320V DC.

SCE9x2 input: 90-264V AC single-phase or three-phase, nominal bus 320V DC (three-phase) or 155V DC (single-phase).

SCE9x3/4/5/6 input: 180-528V AC three-phase, nominal bus 540V (400V AC input) or 650V (480V AC input).

All models are equipped with built-in power supply and brake chopper. The control power supply is 90-264V AC single-phase, with power-off hold function (up to 10 cycles). For SCE902, an external MTE 25CE4 filter is required to achieve CE compliance; For SCE903-906, no external filter is required when the cable length is less than 10 meters.

5.3 Core Features

Full digital control: current loop 62.5 μ s, speed loop 250 μ s, position loop 1ms. Speed loop bandwidth>400Hz, position loop bandwidth>100Hz.

Resolver feedback: 24 bit resolution, repeatability ± 0.08 arcminutes RMS, noise<0.3 arcminutes RMS (unfiltered). Speed feedback accuracy ± 0.01% (typical), ripple 0.75% p-p (1000 rpm, driver itself).

Encoder simulation output: programmable in binary (128-16384 PPR) or decimal (125-16000 PPR), with a maximum output frequency of 833kHz.

I/O：

Differential ± 10V analog input

2-channel ± 5V analog output (can map 28 internal signals, such as speed, current, position error, bus voltage, etc.)

6-way bidirectional digital I/O (BDIO), programmable as input or output, TTL or 24V compatible, open collector electrode output (30V/100mA, BDIO6 is 200mA)

Enable input (optocoupler isolation, 5V or 12V logic threshold optional)

Encoder input (orthogonal/step/direction/addition and subtraction pulses, maximum decoding rate of 800kHz)

+5V/200mA user output

Front panel: Seven segment LED displays status and fault codes (such as "0" indicating no fault and power level disabled, "8" indicating normal enable, flashing codes indicating specific faults).

Environment: Operating temperature 0-50 ° C (full rated current), storage -40-70 ° C, humidity 10-90% without condensation. At an altitude of 1500 meters. SCE900 model CE certification (low voltage directive and EMC directive), SC900 model UL approval.

5.4 Tab Explanation

The core advantage of the SC/SCE900 series lies in three pluggable tabs, which not only add functionality but also serve as carriers for "movable personality parameters".

5.4.1 OC/OCE930 Serial Communication Tab

Function: Provides RS-232 or RS-485 serial interface for parameter setting, automatic tuning, real-time monitoring, and command control.

Software: Comes with 930 Dialogue (Windows 3.1/95 program), supports automatic tuning, parameter upload/download, and variable monitoring.

Removable personality: Drive parameters can be stored in the EEPROM of the tab, and there is no need to reconfigure when replacing the base drive.

Firmware upgrade: The suffix -01 version includes a software upgrade function for the base driver.

5.4.2 OC/OCE940 SERCOS Interface Tab

Function: SERCOS international standard interface (IEC 61491) based on fiber ring network, realizing high-speed real-time data exchange between controller and driver.

Performance: Communication speed up to 16 MHz, supporting up to 16 axes updating position/speed/torque commands every 2 milliseconds.

I/O: The tab comes with 8 optocoupler isolated inputs and 8 outputs (5-30V compatible).

Advantages: One fiber optic cable can replace dozens of analog and encoder cables, with strong anti-interference ability and low wiring costs.

5.4.3 OC/OCE950 Programmable Single Axis Positioning Tab

Function: Transform the SC/SCE900 driver into a complete single axis motion controller with an Intel microcontroller built-in, using the ServoBASIC Plus programming language (BASIC like structure).

Programming environment: Windows development environment, including powerful interactive debuggers, variable monitoring windows, and modular programming.

I/O Expansion: Provides 21 configurable bidirectional digital I/O ports (compatible with Opto-22), along with 6 BDIOs on the base, for a total of 27 I/O. Supports 8 programmable limit switches.

Communication options:

PacLAN: 2.5 Mbaud token ring network, capable of connecting up to 255 drives.

DF-1 protocol (Allen Bradley PLC compatible)

Modbus protocol (compatible with Modicon PLC)

Memory: 32KB NVRAM (optional 128KB), used for storing programs and parameters.

Advanced features: electronic cam, electronic gear, motion interruption, program variable triggering, etc.

5.5 System Connection and Application Topology

SC/SCE900 supports multiple system architectures:

Analog control: The external motion control card outputs a ± 10V speed/torque command, the driver is closed-loop, and the encoder simulates the output feedback to the controller (Figure 1).

Step/direction control: The stepper motor controller sends out a pulse sequence, and the driver completes the position closed loop internally (Figure 2).

Serial port direct control: PC sends position/speed commands through RS-232, suitable for slow or configuration applications (Figure 3).

SERCOS distributed control: The SERCOS master station synchronizes up to 16 drives through a fiber optic ring network (Figure 4).

PacLAN network+programmable I/O: Each axis is equipped with OC950, which exchanges data through PacLAN and communicates with the main station through Modbus/DF-1 via PLC (Figure 5).

Supporting servo motor and system performance

Pacific Scientific provides a complete motor product line for the aforementioned drivers:

PMA series: 55mm to 190mm machine base, continuous torque 0.21-48.5 Nm, peak torque up to 103 Nm. Suitable for high inertia and high rigidity applications.

PMB series: economical, NEMA 17、 The 23 and 34 machine bases have a continuous torque of 0.22-1.40 Nm, suitable for large-scale and cost sensitive applications.

S series: Compact, NEMA 23/34 and metric mounting surfaces, continuous torque 0.5-6.6 Nm.

The system selection table provides recommended motor/driver combinations for 240V, 400V, and 480V busbars, including peak torque, rated speed, continuous current, motor inertia, inductance, and other parameters. For example, the S33D motor with PC3410 driver can provide a peak torque of 12.9 Nm at 240V and a rated speed of 3700 rpm. PMA45Q with SCE9x4 driver provides a peak torque of 21.3 Nm at 400V and a rated speed of 3400 rpm.

Software Tools and Development Support

ToolPAC: Used for PC3400 series, Windows graphical interface, supports point programming, axis setting wizard, tuning wizard, digital oscilloscope.

830Tools: Used for PC800 series, with similar functions, supporting automatic tuning and parameter configuration.

930 Dialogue: Used for SC/SCE900 series (in conjunction with OC930), providing automatic settings, automatic offset adjustment, and variable monitoring.

950 IDE: Used for OC950 programmable tabs, integrated with ServoBASIC editor, compiler, debugger, and supports modular programming.

Optimizer 3.0: Motor selection software that recommends suitable motor and driver combinations after inputting load parameters.