Rockwell Automation 1771-SF1 User Manual

AllenBradley

Servo Interface Module

User

(Cat.

No. 1771-SF1)

Manual

Introduction 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Description 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

User Considerations 12

Component Interfacing, Module Preparation,

and Installation 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Component Encoder 21 Differential Line Drivers 21 Servo Drive Package 21 Isolation 22 Wiring 22 Cable Recommendations 23 Shield Connection 23 Module Preparation 24 Module Keying 27 Specifications 28

Interfacing

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Installation

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26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Programming and Operation 31. . . . . . . . . . . . . . . . . . . . . . .

General 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data Transfers 31 DAC Data (Servo Motor Speed) 31 Control Byte (Servo Motor Amplifier Inhibit) 33 Encoder Counter Values (Position Pulses) 34 Target Values (Position Interrupts) 34 Special Servo Lines on the Backplane 34 Marker 35 A > B 35

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CCW/CW 35 Target Value Interrupt 35 Programming the Servo Control Functions 35

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Introduction

Chapter

Description

User Program

EPROM

Programming

Unit

Plug-in EPROM

The Allen-Bradley Servo Interface Module (Cat. No. 1771-SF1) when used with the Micro Controller (Cat. No. 1771-UC1) can control single axis positioning systems such as found in machine tool applications. When combined with a single motor variable speed drive package and a full quadrature encoder, this microprocessor-controlled servo drive system (Figure 1.1) can be programmed to cycle through precise speed and position profiles.

Figure 1.1

MicroprocessorBased Servo Control System

Typical

User Application

1771- 1771UC1 Micro Controller

SF1 Servo Interface Module

Amplifier Inhibit

Motor Current Inhibit

Velocity

Common

10V

Channels A & B, Channels

(Position Loop, 50KHz Max)

Single-Motor Drive Package

Servo

Amplifier

A & B, Marker, Marker

Controlled Power

Return

(Velocity Loop)

Servo Motor

Tach.

Drive Shaft

Shaft Encoder

Differential Line Driver

10399

11

Chapter 1

Introduction

User Considerations

Operating features described in this manual must be totally programmed in the user software (Z-80A opcodes) of the accompanying micro controller. The servo interface module has the capability to perform as described, provided that the software of the micro controller has been completely developed. The user must assume full responsibility for performing all systems engineering, programming, and software support associated with the micro controller/servo interface module and intended application.

12

Chapter

Component Interfacing, Module Preparation, and Installation

General

Component Interfacing

Encoder

Differential Line Drivers

This chapter describes the necessary characteristics of user-provided components, preparation and installation of the module and wiring considerations. Refer to the Micro Controller Users Manual (Publication No. 1771-6.5.5) for installation of the micro controller module.

The servo interface module must be compatible with other components of the control system, including the differential line drivers, shaft encoder and servo drive package containing the servo motor control amplifier. Required characteristics of these components are stated below.

An encoder should have the following characteristics for monitoring the rotational direction and position of a drive shaft.

Full quadrature, 90o out of phase (typical). Maximum frequency to the servo interface module is 50 KHz for

Channels A, B, and marker.

Line drivers with the following characteristics can be used to transmit encoder quadrature pulses to the servo interface module.

Servo Drive Package

Differential outputs for Channel A, Channel B, and marker. TTL Source and Sink Currents = 15 mA max. TTL Output Voltage = 2.4V (min.) high

= 0.6V (max.) low

Outputs available to the servo motor control amplifier must be compatible with the following control voltage and current levels.

TTL output to inhibit the motor current. TTL output to turn OFF the servo drive amplifier. TTL Output Voltage = 2.4V (min.) high

= 0.6V (max.) low

TTL Sink Current = 12 mA (max.)

21

Chapter 2

Component Interfacing, Module Preparation, and Installation

TTL Source Current = 7.9mA @ 2.4V +10 to -10V DC analog output for forward or reverse proportional

motor speed control.

Isolation

Wiring

None of the terminals of the servo interface module are protected against misapplication of AC, DC, or reverse DC.

CAUTION: Do not apply voltage or current sources to the terminals of the servo interface module except those specified for the terminals. Damage to the module may result.

If voltages are misapplied and damage is done to the terminal-side of the module, the system-side including the data bus to the micro controller is protected to 500V DC maximum isolation from the terminal side of the module.

The line drivers and the servo amplifier of the motor drive package should be wired to the field wiring arm connector of the servo interface module as shown in Figure 2.1.

22

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