ZX Drive #1 ZX Drive #2

The ZX Drive

The Compumotor ZX Drive and motor is a complete Servo System with its own  Inputs and Outputs, capable of complex motions and calculations.   This Drive was made in the late eighties and early nineties.   There are two parts to this system, the motor and drive.

The motor is a 4-pole, three-phase AC brushless motor with built-in rotary  encoder and temperature monitoring.  It is a 5,000 step per  revolution servo motor, capable of providing 9,000 oz-in continuously  or peak of 18,000 oz-in.  The motor has permanent magnets on  the rotor making it synchronous to the frequency supplied by the drive.   Were the motor not synchronous by either permanent magnets or DC  windings on the rotor, (like a regular three phase motor) there would  be a slip of the shaft rotation behind the frequency -- this slip is  necessary to produce torque on all induction and squirrel cage motors.   This would make for inaccurate speed control; motor speed would  be determined by the load as well as frequency.  It would be  almost useless in a precise positioning, velocity & acceleration  control, and would have no holding torque when not in motion.


The drive is made up of two parts, the AC frequency drive and the CPU with  I/O terminals.  The frequency drive is connected directly to  the motor and is controlled by the CPU, making the ZX a self contained  Servo System.  The CPU is receives information from the motor  through the rotary encoder, as well as limit switches placed according  to application (the Home, CW & CCW limits).  The CPU must be  first programmed before it can be used in any application.   This is done by using DOS based XWare software through a Tx/Rx/Vo  RS-232 connection.  The CPU can receive further inputs from a  PLC, switches, thumbwheels and/or a computer terminal.  After  it is programmed, the ZX can be run with or without either a PLC or  computer connection.

The ZX is programmed in a basic programming language made up of commands, and  organized in sequences.  The program is then stored on  battery backed RAM in the CPU (like with a PLC).  Commands  can range from simple Acceleration and Velocity values, I/O  designations, mathematical equations, to more complex logic controls  and Boolean Algebra such as IF/Then, Gosub, And/Or, Else, Until, and  others.  Commands can also be entered through a computer or  through inputs set up to execute commands in the program.

See the ZX/ZXF Indexer Drive User Guide for more information on programming  (pages 26-91), as well as programs listed and explained below.   The ZX/ZXF Indexer Drive Software Reference Guide is not useful for  this purpose; most necessary commands are listed in the User Guide.   The Software Reference Guide is useful after the programming  language and usage is understood, like a dictionary.

Unlike steppers, brushless AC as well as brushless DC motors have the  advantage of good resolution at slow speeds and a lower running  temperature.  Servo motors have a wide verity of uses  including robotics, CNC machinery, indexing, and special conveyor and  lift controls.

- Original Program
- New Program
- New Program Description
- New Sequence Description

Evan Garrett
Paul Adleman
March 20, 2000
2nd year APKG