Introduction to Industrial Automation

 8 

Industrial Networks of PLCs ....................................................................................355

8.1  Topology of a Network .........................................................................................357

8.1.1  Star Topology ...........................................................................................357

8.1.2  Ring Topology .............................................................................................358

8.1.3  Bus Topology ...........................................................................................359

8.2  Communication Protocols ....................................................................................359

8.2.1  Master/Slave Method of Access ............................................................... 360

8.2.2  Carrier Sense with Collision Detection Method of Access ....................... 360

8.2.3  Token Passing Method of Access..............................................................361

8.3  Implementation of Industrial Networks .............................................................. 362

8.3.1  Data Transmission Media. ...................................................................... 362

8.3.2  The ISO/OSI Model ................................................................................... 363

8.3.3  Network Devices ........................................................................................ 364

8.3.4  The Communication Task of PLCs ..........................................................365

8.3.5  The Actuator-Sensor Interface (AS-I) Network. .......................................367

8.3.6  The Profibus Network ............................................................................. 368

8.3.7  SCADA Systems ..................................................................................... 368

Review Questions ............................................................................................................370