1. Industrial communication networks
Lesson 2
Industrial communication networks

2. Industrial Networks
Classified into three levels based upon the type of data and devices that use the network.
Enterprise: non time critical information
Automation and Control: Real time I/O
Field device: switches, output devices and drives

3. Industrial Networks

4. Enterprise Level Shares data between all segments
Transfers non-time critical data
Ethernet is preferred network because high speed, open-source protocol and competitive vendor pool
In the past proprietary networks have been used, but this do not communicate with other networks. Ethernet has been implemented to bridge devices from different networks

5. Automation and Control Level
Transfers data between the controller and the I/O devices it controls and to other controllers
Data is high urgency – real time
Determinism: data to be sent and received in a timely manner and verified is correct
Reliability 24/7 schedule even in hostile environments
Security
Routers typically use to isolate networks and provide security

6. Field Device Level Networks
Connects individual I/O devices to a PLC
Replaces remote I/O racks, adapters, modules, and field wiring with a direct connection to intelligent switches and output devices
Ease of installation
Reduction of I/O wiring
Error and diagnostic reporting
Open networks and support different vendors
Devicenet is the most common field level network for Allen Bradley controllers (others EtherCat, Serial RS-232, CANopen, etc

7. ETHERNET TCP/IP

8. Difference Ethernet/IP and TCP/IP
TCP is an acronym with stands for Transmission Control Protocol. This protocol is responsible for managing the connection between a client and a server
IP has two different meanings depending on how it is used: Industrial Protocol for Ethernet/IP and Internet Protocol for TCP/IP
Ethernet/IP uses the Ethernet infrastructure to manage the connection between various automation devices such as robots, PLCs, sensors, etc. Based on the Common Industrial Protocol
TCP/IP industrial protocol used is Modbus TCP/IP which is responsible for the transmission of the packets. TCP/IP is standard in most programming languages (C,C++, Matlab). Also Modbus TCP/IP is standard in most PCs.

9. Ethernet/IP Is an offspring of the Common Industrial Protocol CIP
Developed for transferring data on DeviceNet and ControlNet (Fieldbus) networks.
Advantage of speed and reliability of Ethernet.
Never truly deterministic however good enough for industry
Real time I/O at 100 Mbps, 20 times faster than ControlNet
No additional hardware needed to communicate to any Ethernet network.

10. Adapters
Connect devices such as controllers, PanelView terminals, drives to other devices
Provide interface that converts data into a signal that can be transmitted on a cable and re-convert that signal back into data at destination device
Make sure devices are Ethernet/IP compatible

11. Cable Cat 5 most common , also known as 10BaseT
Limited to 100 meters between switches and or routers
Can be shielded twisted pair (STP) or unshielded (UTP)
STP thought more expensive than UTP is preferred in areas with high electrical noise, drives > 10 HP, or conductors carrying >100 amps, and if inside metal conduit
Fiber optic run in extreme high electrical noise (immune to noise)
Fiber optic more expensive and needs converters
Fiber optic up to 1500 meters between switches

12. RJ45 Connector Wiring
Category 5 Ethernet Cable uses 8 wires twisted to form four pair of wires.
2 standards for arranging the colors in the RJ45 connector, T568A, and T568B
Cables can be wired straight through or crossover
Straight through: are used to connect devices to switches and routers
Crossover: used to directly connect two Ethernet devices together

13. Crossover cable
Often use to directly connect a computer to an Ethernet/IP module for initial setup. The computer runs a software utility called BootP to set the IP address that the module will use on the network.
A crossover cable reverses the TX and RX lines from one connector to the other to permit connecting a PC directly to an Ethernet Device.
Usually color of cable is red to differentiate

14. Bus (Backbone) Topology

15. Ring Topology

16. Star Topology

17. Star Topology
Connects each device through a separate cable or switch, creating segments or subnets
Eliminates most message collisions (major factor in stablishing determinism)
Allow for new nodes to be installed without disrupting existing nodes
Failure of that node affect only that node
Reduces network traffic by limiting multicast data from going to all nodes on the network by sending only to selected nodes

18. Routers
Used to connect different devices together while maintaining isolation between the networks.
Only messages with the correct address can cross the router from one network to another

19. Switches
Intelligent Ethernet switches have replace hubs to reduce the number of message collisions in the network
Collision occur frequently because more than one node tries to transmit at the same time
Ethernet switch knows the address of each device on each port and stores address in memory. When a message is received, the switch decodes the destination address and sends the message only to the port of which the device is connected
ControlLogix inputs mulitcasts to every node in the network. Intelligent switches can control multicast data, such as I/O to prevent overloading the network with messages