- •24.3 HYDRAULICS
- •24.4 OTHER SYSTEMS
- •24.5 SUMMARY
- •24.6 PRACTICE PROBLEMS
- •24.7 PRACTICE PROBLEM SOLUTIONS
- •24.8 ASSIGNMENT PROBLEMS
- •25. CONTINUOUS CONTROL
- •25.1 INTRODUCTION
- •25.2 CONTROL OF LOGICAL ACTUATOR SYSTEMS
- •25.3 CONTROL OF CONTINUOUS ACTUATOR SYSTEMS
- •25.3.1 Block Diagrams
- •25.3.2 Feedback Control Systems
- •25.3.3 Proportional Controllers
- •25.3.4 PID Control Systems
- •25.4 DESIGN CASES
- •25.4.1 Oven Temperature Control
- •25.4.2 Water Tank Level Control
- •25.5 SUMMARY
- •25.6 PRACTICE PROBLEMS
- •25.7 PRACTICE PROBLEM SOLUTIONS
- •25.8 ASSIGNMENT PROBLEMS
- •26. FUZZY LOGIC
- •26.1 INTRODUCTION
- •26.2 COMMERCIAL CONTROLLERS
- •26.3 REFERENCES
- •26.4 SUMMARY
- •26.5 PRACTICE PROBLEMS
- •26.6 PRACTICE PROBLEM SOLUTIONS
- •26.7 ASSIGNMENT PROBLEMS
- •27. SERIAL COMMUNICATION
- •27.1 INTRODUCTION
- •27.2 SERIAL COMMUNICATIONS
- •27.2.1.1 - ASCII Functions
- •27.3 PARALLEL COMMUNICATIONS
- •27.4 DESIGN CASES
- •27.4.1 PLC Interface To a Robot
- •27.5 SUMMARY
- •27.6 PRACTICE PROBLEMS
- •27.7 PRACTICE PROBLEM SOLUTIONS
- •27.8 ASSIGNMENT PROBLEMS
- •28. NETWORKING
- •28.1 INTRODUCTION
- •28.1.1 Topology
- •28.1.2 OSI Network Model
- •28.1.3 Networking Hardware
- •28.1.4 Control Network Issues
- •28.2 NETWORK STANDARDS
- •28.2.1 Devicenet
- •28.2.2 CANbus
- •28.2.3 Controlnet
- •28.2.4 Ethernet
- •28.2.5 Profibus
- •28.2.6 Sercos
- •28.3 PROPRIETARY NETWORKS
- •28.3.1 Data Highway
- •28.4 NETWORK COMPARISONS
- •28.5 DESIGN CASES
- •28.5.1 Devicenet
- •28.6 SUMMARY
- •28.7 PRACTICE PROBLEMS
- •28.8 PRACTICE PROBLEM SOLUTIONS
- •28.9 ASSIGNMENT PROBLEMS
- •29. INTERNET
- •29.1 INTRODUCTION
- •29.1.1 Computer Addresses
- •29.1.2 Phone Lines
- •29.1.3 Mail Transfer Protocols
- •29.1.4 FTP - File Transfer Protocol
- •29.1.5 HTTP - Hypertext Transfer Protocol
- •29.1.6 Novell
- •29.1.7 Security
- •29.1.7.1 - Firewall
- •29.1.7.2 - IP Masquerading
- •29.1.8 HTML - Hyper Text Markup Language
- •29.1.9 URLs
- •29.1.10 Encryption
- •29.1.11 Compression
- •29.1.12 Clients and Servers
- •29.1.13 Java
- •29.1.14 Javascript
- •29.1.16 ActiveX
- •29.1.17 Graphics
- •29.2 DESIGN CASES
- •29.2.1 Remote Monitoring System
- •29.3 SUMMARY
- •29.4 PRACTICE PROBLEMS
- •29.5 PRACTICE PROBLEM SOLUTIONS
- •29.6 ASSIGNMENT PROBLEMS
- •30. HUMAN MACHINE INTERFACES (HMI)
- •30.1 INTRODUCTION
- •30.2 HMI/MMI DESIGN
- •30.3 DESIGN CASES
- •30.4 SUMMARY
- •30.5 PRACTICE PROBLEMS
- •30.6 PRACTICE PROBLEM SOLUTIONS
- •30.7 ASSIGNMENT PROBLEMS
- •31. ELECTRICAL DESIGN AND CONSTRUCTION
- •31.1 INTRODUCTION
- •31.2 ELECTRICAL WIRING DIAGRAMS
- •31.2.1 Selecting Voltages
- •31.2.2 Grounding
- •31.2.3 Wiring
- •31.2.4 Suppressors
- •31.2.5 PLC Enclosures
- •31.2.6 Wire and Cable Grouping
- •31.3 FAIL-SAFE DESIGN
- •31.4 SAFETY RULES SUMMARY
- •31.5 REFERENCES
- •31.6 SUMMARY
- •31.7 PRACTICE PROBLEMS
- •31.8 PRACTICE PROBLEM SOLUTIONS
- •31.9 ASSIGNMENT PROBLEMS
- •32. SOFTWARE ENGINEERING
- •32.1 INTRODUCTION
- •32.1.1 Fail Safe Design
- •32.2 DEBUGGING
- •32.2.1 Troubleshooting
- •32.2.2 Forcing
- •32.3 PROCESS MODELLING
- •32.4 PROGRAMMING FOR LARGE SYSTEMS
- •32.4.1 Developing a Program Structure
- •32.4.2 Program Verification and Simulation
- •32.5 DOCUMENTATION
- •32.6 COMMISIONING
- •32.7 REFERENCES
- •32.8 SUMMARY
- •32.9 PRACTICE PROBLEMS
- •32.10 PRACTICE PROBLEM SOLUTIONS
- •32.11 ASSIGNMENT PROBLEMS
- •33. SELECTING A PLC
- •33.1 INTRODUCTION
- •33.2 SPECIAL I/O MODULES
- •33.3 SUMMARY
- •33.4 PRACTICE PROBLEMS
- •33.5 PRACTICE PROBLEM SOLUTIONS
- •33.6 ASSIGNMENT PROBLEMS
- •34. FUNCTION REFERENCE
- •34.1 FUNCTION DESCRIPTIONS
- •34.1.1 General Functions
- •34.1.2 Program Control
- •34.1.3 Timers and Counters
- •34.1.4 Compare
- •34.1.5 Calculation and Conversion
- •34.1.6 Logical
- •34.1.7 Move
- •34.1.8 File
- •34.1.10 Program Control
- •34.1.11 Advanced Input/Output
- •34.1.12 String
- •34.2 DATA TYPES
plc network - 28.23
Figure 28.17 A Box Loading System
28.6SUMMARY
•Networks come in a variety of topologies, but buses are most common on factory floors.
•The OSI model can help when describing network related hardware and software.
•Networks can be connected with a variety of routers, bridges, gateways, etc.
•Devicenet is designed for interfacing to a few inputs and outputs.
•Controlnet is designed for interfacing between controllers.
•Controlnet and devicenet are based on CANbus.
•Ethernet is common, and can be used for high speed communication.
•Profibus is another control network.
28.7PRACTICE PROBLEMS
1.Explain why networks are important in manufacturing controls.
2.We will use a PLC to control a cereal box filling machine. For single runs the quantities of cereal types are controlled using timers. There are 6 different timers that control flow, and these result in different ratios of product. The values for the timer presets will be downloaded from another PLC using the DH+ network. Write the ladder logic for the PLC.
3.
a)We are developing ladder logic for an oven to be used in a baking facility. A PLC is controlling the temperature of an oven using an analog voltage output. The oven must be started with a push button and can be stopped at any time with a stop push button. A recipe is used to control the times at each tempera-
plc network - 28.24
ture (this is written into the PLC memory by another PLC). When idle, the output voltage should be 0V, and during heating the output voltages, in sequence, are 5V, 7.5V, 9V. The timer preset values, in sequence, are in N7:0, N7:1, N7:2. When the oven is on, a value of 1 should be stored in N7:3, and when the oven is off, a value of 0 should be stored in N7:3. Draw a state diagram and write the ladder logic for this station.
b)We are using a PLC as a master controller in a baking facility. It will update recipes in remote PLCs using DH+. The master station is #1, the remote stations are #2 and #3. When an operator pushes one of three buttons, it will change the recipes in two remote PLCs if both of the remote PLCs are idle. While the remote PLCs are running they will change words in their internal memories (N7:3=0 means idle and N7:3=1 means active). The new recipe values will be written to the remote PLCs using DH+. The table below shows the values for each PLC. Write the ladder logic for the master controller.
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button A |
button B |
button C |
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13 |
17 |
14 |
PLC #2 |
690 |
235 |
745 |
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45 |
75 |
34 |
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76 |
72 |
56 |
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345 |
234 |
645 |
PLC #3 |
987 |
12 |
23 |
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345 |
34 |
456 |
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764 |
456 |
568 |
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87 |
67 |
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4.A controls network is to be 1500m long. Suggest three different types of networks that would meet the specifications.
5 How many data bytes (maximum) could be transferred in one second with DH+?
6.Is the OSI model able to describe all networked systems?
7.What are the different methods for resolving collisions on a bus network?
28.8 PRACTICE PROBLEM SOLUTIONS
1.These networks allow us to pass data between devices so that individually controlled systems can be integrated into a more complex manufacturing facility. An example might be a serial connection to a PLC so that SPC data can be collected as product is made, or recipes downloaded as they are needed.
plc network - 28.25
2.
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DEST. #T4:0.PRE |
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T4:1 |
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T4:5 |
fill hearts |
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T4:1/TT |
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fill moons |
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ETC...
plc network - 28.26
3.
a) |
start |
stop |
T4:2/DN |
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on N7:3/0 |
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MOV |
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on N7:3/0 |
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Source N7:0 |
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Dest T4:0.PRE |
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Source N7:1 |
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Dest T4:1.PRE |
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Source N7:2 |
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Dest T4:2.PRE |
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TON |
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Timer T4:0 |
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T4:0/DN |
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Delay 0s |
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Timer T4:1 |
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T4:1/DN |
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Delay 0s |
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Timer T4:2 |
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Delay 0s |
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BT10:0/EN |
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Block Transfer Write |
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Module Type Generic Block Transfer |
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Rack 000 |
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Group 3 |
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Module 0 |
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Control Block BT10:0 |
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Data File N9:0 |
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Length 13 |
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T4:0/TT |
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Continuous No |
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Source 2095 |
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Dest N9:0 |
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T4:1/TT |
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Source 3071 |
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T4:2/TT |
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Source 3686 |
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Source 0 |
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Dest N9:0 |
plc network - 28.27
b) |
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MG9:0/EN |
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MG9:1/EN |
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MG9:3/EN |
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Control Block MG9:2 |
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(ER) |
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MSG |
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(EN) |
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Send/Rec Message |
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(DN) |
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Control Block MG9:3 |
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(ER) |
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MG9:0 |
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MG9:1 |
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MG9:2 |
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MG9:3 |
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Read/Write |
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Write |
Read/Write |
Write |
Read/Write |
Read |
Read/Write |
Read |
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Data Table |
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N7:40 |
Data Table |
N7:43 |
Data Table |
N7:3 |
Data Table |
N7:3 |
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Size |
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3 |
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Size |
6 |
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Size |
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1 |
Size |
1 |
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Local/Remote Local |
Local/Remote Local |
Local/Remote Local |
Local/Remote Local |
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Remote |
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N/A |
Remote |
N/A |
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Remote |
N/A |
Remote |
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Link ID |
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N/A |
Link ID |
N/A |
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Link ID |
N/A |
Link ID |
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Remote Link |
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N/A |
Remote Link N/A |
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Remote Link |
N/A |
Remote Link |
N/A |
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Local Node |
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2 |
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Local Node |
3 |
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Local Node |
2 |
Local Node |
3 |
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Processor |
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PLC-5 |
Processor |
PLC-5 |
Processor |
PLC-5 |
Processor |
PLC-5 |
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Dest. Addr. |
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N7:0 |
Dest. Addr. |
N7:0 |
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Dest. Addr. |
N7:0 |
Dest. Addr. |
N7:1 |
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A |
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N7:0/0 |
N7:0/1 |
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COP |
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Source N7:10 |
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Dest N7:40 |
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Length 9 |
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B |
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N7:0/0 |
N7:0/1 |
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COP |
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Source N7:20 |
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Dest N7:40 |
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Length 9 |
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C |
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N7:0/0 |
N7:0/1 |
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COP |
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Source N7:30 |
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Dest N7:40 |
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Length 9 |
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N7:10 |
13 |
690 |
45 |
76 |
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345 |
987 |
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345 |
764 |
87 |
0 |
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N7:20 |
17 |
235 |
75 |
72 |
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234 |
12 |
34 |
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456 |
67 |
0 |
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N7:30 |
14 |
745 |
34 |
56 |
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645 |
23 |
456 |
568 |
8 |
0 |
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