An Introduction to Laboratory Automation

VICTOR CERDÄ

Department of Chemistry University of the Balearic Islands

Palma de Mallorca, Spain

GUILLERMO RAMIS

Department of Analytical Chemistry University of Valencia

Burjassot, Valencia, Spain

A WILEY-INTERSCIENCE PUBLICATION

John Wiley & Sons, Inc. NEW YORK / CHICHESTER / BRISBANE / TORONTO / SINGAPORE

CONTENTS

CHAPTER 1 AUTOMATION AND CHEMISTRY 1

1.1. Introduction 1 1.2. Automation of the Different Steps of an

Analytical Control Process 2 1.3. Computer Operation Modes 4 1.4. Setting Out an Automation Problem 6

CHAPTER 2 BASIC CONCEPTS AND ELEMENTS OF ANALOG ELECTRONICS 7

2.1. Introduction 7 2.2. Simplified Representation of Circuits 8 2.3. Resistors 9

2.3.1. Introduction 9 2.3.2. Voltage Divider 9

2.4. Signals and Noise 10 2.5. Logic Levels 11 2.6. Capacitors, RC Circuits, and Applications 13

2.6.1. Capacitors 13 2.6.2. RC Circuits 14 2.6.3. Differentiators and Integrators 15 2.6.4. Ramp Generators 17

2.7. Diodes, LEDs, and Zeners 18 2.8. Rectification and Filtering 20 2.9. Integrated Circuits 22 2.10. Regulators 23

2.10.1. Introduction 23 2.10.2. Three-Terminal Regulators 24 2.10.3. Four-Terminal Regulators 24

vn

viii CONTENTS

2.11.

2.12

2.13

2.14

2.15. 2.16

2.10.4. Voltage Regulation of Large Load Currents

Transistors 2.11.1. 2.11.2.

2.11.3. 2.11.4. 2.11.5.

Introduction Phototransistors and Isolation Techniques Transistor Switching Emitter Follower Field-Effect Transistors (FETs)

Operational Amplifiers 2.12.1. 2.12.2. 2.12.3. 2.12.4. 2.12.5. 2.12.6. 2.12.7. 2.12.8. 2.12.9.

2.12.10

2.12.11

2.12.12

Introduction The Response of an OA Inverting Amplifier Noninverting Amplifier OA-Based Voltage Follower OA-Based Current Sources Current-to-Voltage Conversion Summing Amplifier OA-Based Integrators and Differentiators Voltage Regulators Based on the 723 IC Single Power Supply and Multiple OAs BIFET and BIMOS Amplifiers

Comparators 2.13.1. 2.13.2. 2.13.3.

Introduction The Shmitt Trigger A Window Comparator

Differential Amplifiers 2.14.1. 2.14.2.

Introduction Instrumentation Amplifiers

Isolation Amplifiers Oscillators

25 26 26

28 29 31 32 35 35 37 39 41 41 42 43 44

45

46

50 51 52 52 53 54 56 56 57 61 61

CHAPTER 3 DIGITAL ELECTRONICS 65

3.1. Introduction 65

CONTENTS IX

3.2. 3.3.

3.4.

3.5.

3.6.

3.7.

3.8.

3.9.

3.10

3.11

Bits, Bytes, Words, and Digital Signals The Binary, Octal, and Hexadecimal Codes

Other Digital Codes

Gates 3.5.1. 3.5.2. 3.5.3. 3.5.4. 3.5.5. 3.5.6.

Introduction The AND and NAND Gates Inverters and Separators The OR, NOR, and XOR Gates Combinations of Gates Gates of the TTL Family

Latches 3.6.1. 3.6.2. 3.6.3.

Introduction Timing Diagrams Description of Some Common Latches

Encoder-Decoders

Counters 3.8.1. 3.8.2. 3.8.3.

Introduction The 7490 IC Decade Counter Other Counters

Monostable Multivibrators 3.9.1. 3.9.2. 3.9.3. 3.9.4. 3.9.5.

3.9.6.

Buses 3.10.1. 3.10.2.

Introduction The 74121 Monostable Multivibrator The 74122 Monostable Multivibrator The 555 Timing Circuit Use of the 555 as a Monostable Multivibrator Use of the 555 as an Astable Multivibrator

Introduction Devices with a Three-State Logic

Multiplexers and Demultiplexers 3.11.1. 3.11.2.

Analog Multiplexers Digital Multiplexers

65 66

67

68 68 70 72 73 74 75

75 75 77

78

81

83 83 84 86

87 87 87 89 90

92

94

95 95 96

97 97

100

x CONTENTS

CHAPTER 4 MICROPROCESSORS

4.1. 4.2. 4.3. 4.4.

4.5. 4.6. 4.7. 4.8. 4.9.

4.10

4.11 4.12

Introduction Hardware, Software, and Firmware Memory Architecture of the Intel 8085 jmP 4.4.1. 4.4.2. 4.4.3.

4.4.4. 4.4.5. 4.4.6.

Introduction The 8085 uP Parts Bus Structure and ALU Operation Mode The Register of States Internal Registers Instruction Register, Decoder, and Control Units

|iP Instructions uP-Based Systems The RAM Memory The ROM Memories I/O Techniques 4.9.1. 4.9.2. 4.9.3.

Polling Interruption Direct Memory Access

I/O Devices 4.10.1. 4.10.2.

4.10.3.

4.10.4.

4.10.5.

The UART Introduction to Parallel I/O Interfaces The Intel 8355 ROM with Programmable I/O Facilities The Motorola 6522 Versatile Interface Adapter The Complex Interface Adapters (CIAs)

The Intel SDK-85 Kit Monitor Routines

103

103 104 104 106 106 106

108 110 111

112 113 115 116 116 117 117 118 118 119 119

119

121

121

122 122 127

CHAPTER 5 TRANSDUCTION, SIGNAL CONDITIONING, DATA ACQUISITION, AND CONTROL 131

5.1. Introduction 131

CONTENTS XI

5.2.

5.3.

5.4.

5.5.

5.6.

Transducers 5.2.1. 5.2.2. 5.2.3. 5.2.4. 5.2.5.

Introduction Temperature Transducers Light Transducers Pressure Transducers Other Transducers

Signal Conditioning 5.3.1. 5.3.2. 5.3.3.

Introduction The Wheatstone Bridge Signal-to-Frequency Converters

A/D and D/A Converters 5.4.1. 5.4.2.

5.4.3. 5.4.4. 5.4.5.

Introduction Precision in A/D and D/A Converters D/A Converters A/D Converters Use of Analog Multiplexers with A/D and D/A Converters

Programming Interface Cards in BASIC 5.5.1. 5.5.2. 5.5.3.

5.5.4.

5.5.5.

Introduction Device Addresses Programming Interface Cards in Interpreted BASIC Programming Interface Cards in Compiled BASIC Other BASIC Instructions that Are Useful in Automation

Description of Some Commercial Interface Cards 5.6.1. 5.6.2.

5.6.3. 5.6.4.

[MUN

The MetraByte DASH-8 Card The Data Translation DT2811 Board Series The Fischertechnik Interface A Homemade Interface for Control of Injection Valves

ICATIONS

Introduction

131 131 132 136 139 139 140 140 140 142 144 144

144 145 148

156 156 156 157

159

166

169

170 171

174 177

179

183

183

Xll CONTENTS

6.2.

6.3.

The RS232C Serial Communication Standard 6.2.1. 6.2.2.

6.2.3. 6.2.4.

6.2.5.

6.2.6.

Introduction Specifications of the RS232C Protocol Transmission Method Programming Serial Communications with the Commodore VIC-20 and 64 Microcomputers Programming Serial Communications with the Amstrad CPC-6128 Microcomputer Programming Serial Communications with the IBM PC and Compatible Personal Computers

The IEEE488 Interface 6.3.1. 6.3.2. 6.3.3. 6.3.4. 6.3.5. 6.3.6.

6.3.7.

Introduction Controllers, Listeners, and Talkers Device Addresses The IEEE488 Bus Interface Functions Programming of IEEE488 Commercial Cards Assembly Language Subroutines of the CEC PC< = >488 Card

CHAPTER 7 INSTRUMENTS AND APPARATUS FOR LABORATORY AUTOMATION

7.1. 7.2. 7.3. 7.4. 7.5. 7.6. 7.7. 7.8.

Introduction The Keithley 175 Multimeter Potentiometers Spectrophotometers Spectrofluorimeters Automatic Balances Burettes and Dosifiers Samp lers

183 183

184 187

188

192

197 205 205 206 207 208 210

211

213

227

227 228 234 237 240 244 247 250

CONTENTS xiii

7.8.1. The Crison MicroSAMPLER 2040 250 7.8.2. A Homemade Sampler Based on a

Fischertechnik Kit 252

CHAPTER 8 AUTOMATION OF ANALYTICAL METHODS 255

8.1. Introduction 255 8.2. Automation of Potentiometrie Titrimetry 256

8.2.1. Introduction 256 8.2.2. Automation of Potentiometrie

Titrations Using a Commodore VIC-20 Microcomputer 256

8.2.3. Automation of Potentiometrie Titrations Using an IBM PC 257

8.2.4. Automatic Determination of Boric Acid 259

8.2.5. An Automatic System for Ion-Selective Potentiometry 261

8.2.6. Automatic Potentiometrie Titrimetry with Electrogenerated Reagents 262

8.3. Automation of Potentiometrie Stripping Analysis 263 8.3.1. Introduction 263 8.3.2. Automatic System for PSA Based

on a VIC-20 Microcomputer 264 8.3.3. Automatic System for PSA

with Galvanostatic Oxidation Option Based on an IBM PC 269

8.4. An Automatic System for Conductimetric Titrimetry 271

8.5. Automation of Spectrophotometric Methods 272 8.5.1. Automation of Photometrie

Titrations 272 8.5.2. An Automatic System for

Spectrophotometric-Potentiometric Titrations 273

8.5.3. Data Acquisition System for Spectrophotometric-Kinetic Methods 274

xiv CONTENTS

8.6. Automation of Fluorimetric Methods 276 8.7. Automation of Calorimetric Methods 280

8.7.1. A System for Automatic Thermometric Titrations 280

8.7.2. Automation of a Batch Calorimeter 282 8.8. Automation of Flow Injection Analysis

(FIA) 283 8.8.1. Introduction 283 8.8.2. An Automatic FIA System for the

Simultaneous Determination of Nitrates and Nitrites in Waters 284

CHAPTER 9 LABORATORY ROBOTICS

9.1. 9.2.

9.3.

9.4.

9.5.

9.6.

Introduction Motors 9.2.1. 9.2.2. 9.2.3. 9.2.4. 9.2.5.

Introduction Synchronous Motors Direct Current Motors Servo Motors Stepper Motors

Position Detectors 9.3.1. 9.3.2. 9.3.3. 9.3.4. 9.3.5. 9.3.6.

Introduction Mechanical Switch Closures Noncontact Position Detectors Potentiometers Shaft Encoders Tachometers

Articulated Arms 9.4.1. 9.4.2.

Introduction Features of Articulated Arms

The Training Program of the Fischertechnik Prototype Robot Laboratory Unit Operations

289

289 290 290 291 291 291 292 294 294 295 296 296 297 298 299 299 300

304 304

RECOMMENDED BIBLIOGRAPHY 307

INDEX 311