Numerical Control Systems
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V. Sosonkin, G. Martinov
Text book (in Russian)
ISBN 5-98704-012-4
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CONTENTS
List of abbreviations............................................................................................... 10
Foreword................................................................................................................. 13
Introduction............................................................................................................ 14
Chapter 1. Classification of NC systems................................................................. 17
1.1. Current world level of NC architectural solutions ............................................... 17
1.1.1. CNC and PCNC-1 systems............................................................................. 19
1.1.2. PCNC-2 systems....................................................................................... 21
1.1.3. PCNC-3 systems....................................................................................... 23
1.1.4. PCNC-4 systems....................................................................................... 22
1.2. Integration based on open control and OPC
standard (OLE for Process Control) ........................................................................ 32
1.2.1. Notions about open control....................................................................... 32
1.2.2. SCADA.................................................................................................... 36
1.2.3. OPC standard........................................................................................... 38
1.3. Integration based on STEP production
standards (Standard for the Exchange of Product model data)................................. 44
1.3.1. Review of STEP production standards......................................................... 44
1.3.2. STEP-NC.................................................................................................. 46
1.3.3. Using EXPRESS and XML in NC interfaces................................................... 52
Chapter 2. General principles of building NC systems........................................... 55
2.1. Architecture of PCNC systems.......................................................................... 55
2.1.1. New generation of NC systems.................................................................. 55
2.1.2. Modular NC architecture at the application level.......................................... 57
2.1.3. Open architecture of NC systems............................................................... 59
2.1.4. Virtual model of the PC-subsystem inside NC............................................. 62
2.2. Problem of real time in control systems............................................................ 63
2.2.1. Way the problem is put............................................................................ 63
2.2.2. Real time in control systems..................................................................... 64
2.2.3. Basic notions of real-time operating systems.............................................. 64
2.2.4. Using Windows NT in control systems........................................................ 65
2.2.5. Strategy of dispatching based on RTX extension......................................... 66
2.2.6. Principle of organizing and dispatching
threads in NC software....................................................................................... 68
2.3. Problems of cycle-logic control......................................................................... 71
2.3.1. Classification of cycle-logic control systems................................................ 71
2.3.2. System of notions used, when organizing
cycle-logic control............................................................................................. 72
2.3.3. Structure of the cycle logic control system (the client part)......................... 74
2.3.4. Alternative structures of the project in its client part.................................. 76
2.3.5. Work of the cycle-logic control system in its server part.............................. 78
2.3.6. Object-oriented approach in cycle logic control........................................... 80
2.3.7. Peculiarities of cycle-logic controlling NC machine-tools.............................. 83
2.4. Building intra-modular communication medium................................................ 87
2.4.1. Basic functions of communication medium................................................. 88
2.4.2. Data requests and client-server transactions.............................................. 91
2.4.3. Virtual structure of the object-oriented bus................................................ 95
2.4.4. Communication medium built like open modular system............................. 97
2.5. Principles of implementing remote NC terminals................................................ 99
2.5.1. Remote terminal of the control system..................................................... 100
2.5.2. Computer technologies used, when
developing the remote terminal......................................................................... 100
2.5.3. Áèáëèîòåêè êëàññîâ Java libraries used, when
implementing applets....................................................................................... 102
2.5.4. Software tools used, when developing the remote terminal........................ 105
2.5.5. Specifics of NC system’s remote terminal................................................. 106
2.6. Architectural peculiarities of NC systems,
supporting ISO 14649 STEP-NC........................................................................... 107
2.6.1. STEP-NC standard as opposed to traditional
programming of NC machine tools..................................................................... 108
2.6.2. EXPRESS language................................................................................. 111
2.6.3. Processes and resources in STEP-NC........................................................ 113
2.6.4. Mixed architecture.................................................................................. 118
Chapter 3. Control tasks....................................................................................... 121
3.1. Geometric control task................................................................................... 121
3.1.1. Interpreter of flow programs................................................................... 122
3.1.2. Interpolator........................................................................................... 127
3.2. Cycle-logic control task................................................................................. 134
3.2.1. Formal description of logic cycles............................................................ 135
3.2.2. Software tools, supporting visual
programming of logic cycles............................................................................. 140
3.2.3. Software tool, generating Ñ++
codes of cycle-logic executable modules............................................................. 140
3.3. SoftPLC used for cycle-logic control of NC machine-tools................................... 142
3.3.1. Object-oriented approach in SoftPLC software............................................ 142
3.3.2. SoftPLC architecture................................................................................ 143
3.3.3. SoftPLC software..................................................................................... 147
3.3.4. CANbus-interface.................................................................................... 151
3.4. Terminal (HMI) control task............................................................................ 155
3.4.1. Interpreter of operator dialog in Windows-interface................................... 155
3.4.2. Specifics of building ISO-7 bit
editor (inside the terminal task)....................................................................... 161
3.4.3. High level flow-programs’ editor-debugger
(inside the terminal task)................................................................................ 165
3.5. Realization of the diagnostic control task........................................................ 168
3.5.1. Notions about the diagnostic process...................................................... 168
3.5.2. Structure of the diagnostic sub-system................................................... 169
3.5.3. Realization of the logic analyzer ............................................................. 172
3.5.4. Realization of oscilloscope...................................................................... 174
Chapter 4. Technologies of control-systems’
software implementation.................................................................................... 178
4.1. Technology of object-oriented programming................................................... 178
4.1.1. Comparison of programming technologies............................................... 179
4.1.2. Basic notions of object-oriented approach............................................... 180
4.1.3. Methods of choosing objects in control systems....................................... 184
4.1.4. Structure of control-systems’ software.................................................... 185
4.1.5. Software-tools’ support of object-oriented
programming and G. Booch’es formal methods................................................. 186
4.2. Specifics of object-oriented programming...................................................... 188
4.2.1. Elements of PCNC abstract model........................................................... 189
4.2.2. Object-oriented model of PCNC systems’ modules................................... 191
4.2.3. Object-oriented model of imaging data................................................... 193
4.3. Methodical aspects of building open NC systems............................................ 197
4.3.1. Notions about open NC systems............................................................. 199
4.3.2. PCNC as open control system................................................................. 200
4.3.3. Building NC systems like open language processor................................... 201
4.3.4. Standard facilities of open-architecture support....................................... 204
4.3.5. Standard software tools supporting open architecture.............................. 208
4.3.6. Original software tools supporting open
architecture of NC systems............................................................................. 213
4.3.7. Environment of developments............................................................. 215
4.4. Technology of component software............................................................... 217
4.4.1. Basic notions....................................................................................... 218
4.4.2. Servo drive controller illustrating component approach............................ 221
4.4.3. Classification of COM-interfaces and COM-servers................................... 223
4.4.4. Area of COM applications...................................................................... 226
4.4.5. Software tools supporting component development................................ 227
4.4.6. Example of ATL COM-server................................................................ 229
Chapter 5. NC user documents.......................................................................... 231
5.1. Structure of programming guide.................................................................. 231
5.1.1. Phase space of technological machine................................................... 232
5.1.2. Raise of flow-programs’ level................................................................ 236
5.1.3. Control system functionality reflected
in flow program version................................................................................. 238
5.2. NC system configuration............................................................................. 246
5.2.1. Representation of configuration parameters in NC system....................... 246
5.3. Methods of programming NC machine tools.................................................. 252
5.3.1. Basic notions....................................................................................... 252
5.3.2. Coordinate axes and coordinate systems............................................... 254
5.3.3. Trajectories of movements (types of interpolation)................................. 263
5.3.4. Grouping coordinate axes (G581, G580)................................................ 270
5.3.5. Spindle control.................................................................................... 273
5.4. Methods of implementing NC flow programs
in accordance with the standard, ISO 14649 STEP-NC........................................ 274
5.4.1. XML Spy software tool.......................................................................... 275
5.4.2. Schemas of flow programs according to
the STEP-NC standard................................................................................. 276
Literature........................................................................................................... 287
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