ServoWire Axis Module

The ServoWire Axis Module provides high performance motion control utilizing up to eight axes of servomotors and/or remote encoders.

ServoWire Axis Modules are metal-edged printed circuit boards which plug conveniently into the 16-bit ISA backplane of the ORION® motion controller, and use a 80 MHz Texas Instruments digital signal processor (DSP) to provide axis control algorithms. The Axis Module also includes diagnostic LEDs, MotionDATA electronic gearing, ServoWire network interfaces, and optional analog inputs.

Depending on the requirements of the application, the servo loop update on the Axis Module can be configured up to 2kHz (eight servos) or 4kHz (four servos).

Multi-Processor Architecture: The DSP on the Axis Module is interfaced to the main Intel architecture processor through a 16K byte shared memory for maximum speed and flexibility.  The resulting multiprocessor architecture, combined with the overall power of the DSP, enables ORION® to operate effectively at high sampling rates to provide accurate positioning via robust motion control algorithms. It also eliminates analog components including tachometers.

ServoWire Network Interface: Reliable, simple to configure, scalable, all digital control interface to the ServoWire motor/drive axes.

MotionDATA: For multi-axis tightly synchronized motion control applications, MotionDATA provides a direct axis module to axis module communications link to share motion reference information at loop update rates. This synchronous data communications channel operates at 625 Kbits per second and utilizes user-transparent error correction techniques.  MotionDATA speed and flexibility allows large systems to be precisely electronically geared to a single electronic lineshaft or multiple sub-lineshafts in a cascaded control configuration.

ServoWire Axis Module Options
Analog Inputs: This option provides four or eight12-bit analog inputs that allow external devices to interface to the servo control loop. Software configured digital filtering eliminates having to install external filtering components on the analog input.

ServoWire Drive Network Overview

ServoWire uses IEEE-1394 to create a potent architecture for multi-axis motion control and synchronization. The system uses the IEEE-1394 memory mapped model where all drive setup and motion control parameters are defined as software variables and communicated in real-time over the IEEE- 1394 bus.

Servo loops are managed in real-time over the bus, implementing a digital torque control network for up to 8 axes and eliminating all digital-to-analog conversions. Actual torque commands to the drives are transmitted digitally as 16-bit variables, eliminating the cost and limitations of traditional 12-bit, D-to-A converters and analog torque signals.  Digital torque control combines the fundamental advantages of torque-mode control (greater control flexibility, acceleration feedforward and torque information) with the advantages of digital networking and performance.

In this digital system, a velocity observer eliminates the need for an analog tachometer, and all potentiometers are replaced by software parameters. All loop adjustments are automatically computed when a motor, load inertia and the velocity loop time constant are selected from a configuration software menu. System parameters such as "peak motor output torque" are also set in software.  With the elimination of analog conversions, the ServoWire drive network provides both high bandwidth and outstanding noise immunity. Digital servo loops (including 32-bit intermediate results on calculations) provide precise control algorithms that result in drift-free operation.

The user’s application program can easily adjust for changing factors (i.e. -- load inertia) by dynamically changing drive settings or loop parameters. An all-software torque-mode positioning system also provides outstanding performance monitoring, with easily accessible real-time values for position, velocity, acceleration and torque.

• Texas Instruments Digital Signal Processor (DSP) operating at 80 MHz.
• MotionDATA communications provides tightly coordinated, multi-axis electronic gearing. Connectors provide method for linking MotionDATA between adapters.
• 16K byte shared memory interface to main processor to queue motion commands from MotionBASIC®
• 128K byte on-board memory for DSP program and data space, as well as motion profile and cam data

• Direct digital control of drive through the ServoWire Network with update rates to 5 kHz (configuration dependent) provide wide bandwidth for high positioning accuracy & response
• Position, velocity or torque control supported.
• Full 32-bit position count or modulo position in user’s units.
• Elimination of analog interface errors and extremely quiet servo loop operation using direct digital processing of both position and velocity with 32 bit intermediate calculation accuracy
• Software controlled position, speed, and current limits
• Velocity and acceleration feedforward for minimum tracking errors and response times

• High speed industry standard platform (IEEE-1394) providing drive isolation and reliable connections to up to eight ServoWire drives.
• Each Axis Module provides three network interface connectors for flexibility configuring connections on the ServoWire network.
• ServoWire drive remote enable, reset functions, status monitoring, motor parameter configuration and firmware updates provided through the ServoWire Network.

• Status Indicators: Axis Module, MotionDATA Status, and ServoWire Network status
• Axis Status Indicators: Dual color status led for each drive on the network

• Four or eight optional analog inputs on two pluggable terminal blocks.

ServoWire Axis Module: At A Glance

• Plug and Play Convenience
  No address jumpers to set. Axis Modules are automatically recognized and configured by the ORION® controller. Dual port multiprocessor architecture interfaces the MotionBASIC® programming language to the on-board Digital Signal Processor (DSP) through the ISA bus.
• Diagnostic LEDs
  Three system status LEDs (DSP OK, MotionDATA active, and ServoWireTM network) plus eight dual-color axis status LEDs give consistent indication of system integrity.
• MotionDATA Electronic Gearing
  Axis module to Axis module link transporting servomotor or encoder position information between multiple drives on different networks.
• ServoWire Drive Network
  Standard IEEE-1394 cables, high-speed network communication to eight servodrives. All drive parameters downloaded at power-up. Straightforward drive setup process, real-time drive parameter changes allowed. Extensive alarm and fault status reporting for each drive.
• Analog Inputs
  Option to add four or eight channels of 12-bit analog to digital converters with digital filters provided to interface external control devices.

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