Network Backbone Basics: Hubs, Bridges, Switches, and Gateways

As the process industry steadily moves to wireless networking components, its important to understand the basics. This post and the video below describe four key backbone components for data networking.

Signal flow and data transfer are assisted within a network by various devices known as backbones. The four different backbone devices are hubs, bridges, switches, and gateways. Each device transports data in a specific way.

A hub is a centralized connecting device. Often located at a center of a star network that automatically rebroadcasts any signal or data that it receives from one device to all other devices on the network. Because all the devices connected to a hub are competing for media usage, it's possible for collisions to occur when two devices send transmissions simultaneously. For this reason, it's important to avoid using a hub for messaging that requires immediate response.

Another network backbone device is called a bridge. Network bridges are smart devices that process and record information about signal traffic between devices in the networks. The bridge then uses this information to determine the most efficient path for data transfer, between a transmitting and a receiving device, without having to send it to every device in the network.

A switch is a multi-port network bridge that uses packet switching to forward data to one or multiple specific devices. Because more than one transmission can occur at a time, switch operating speeds are very fast. Switches are also full duplex devices that allow data signals to flow simultaneously in both directions. This eliminates the risk of data collisions that may occur in other network backbone devices.

When two segments of the same network have different communication formats a gateway is needed to connect them. A gateway performs a conversion function so that a computer on an Ethernet network using a TCP/IP protocol may communicate with a PLC on a subnet using the ControlNet protocol. Even though these two protocols are incompatible, the gateway can connect them on the same network and allow them to function together. Hubs, bridges, switches, and gateways - the backbones of networking - perform individual and important functions in keeping networks performing at their highest level.

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Wireless Instrumentation for the Process Control Industry

Analynk wireless instruments have been successfully implemented in process control applications including temperature measurements, 4 to 20mA bridges, discrete inputs/outputs, pulse inputs, lighting and pump controls. Contact Analynk Wireless today to discuss your plant's wireless requirements.

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614-755-6091

Wireless for Safety

Wireless systems may be useful to enhancing the safety profile within a factory operation. These systems can be used to prevent injury through improved communication and enhanced situational awareness within the factory. Wireless safety systems are used in many applications including those designed to prevent chemical handling mishaps, avoid heavy equipment accidents such as “struck-by, and back-over” incidents, prevent falls through active position monitoring and safety interconnects, provide situational awareness within confined spaces, and improve safety for non-employees.

Along with adaption of wireless sensor networks for industrial automation, there are more applications of wireless technology created by users after they are more familiar and comfortable with the wireless technology. Also because of the strong benefits of wireless applications that can save project execution time and cost, more and more wireless has been used for secondary or backup systems for time-critical application such as safety or control applications. Based on this movement, ISA-84 working group (WG) 8 developed a technical report on wireless for safety systems other than those of a safety integrated system (SIS), i.e., those systems with a system integrity level (SIL) rating below ten. The technical report describes the additional elements needed to be addressed when wireless technology is used in an Independent Protection Layer (IPL). Refer to the ISA technical report TR84.00.08-2017 Guidance for Application of Wireless Sensor Technology to Non-SIS Independent Protection Layers for more information.

Reprinted from "Guide to Industrial Wireless Systems Deployments" by the National Institute of Standards and Technology. Get your copy here.

Business Case for Industrial Wireless

One of the key enablers of factory automation is the availability of wireless radio frequency devices. Some applications of radio frequency devices include process control, oil and gas refineries, pharmaceuticals, food and beverage, autonomous guided vehicles (AGVs) control, slotted microwave guides, pendants to control cranes and machine tools, active and passive radio frequency identifier (RFID) for tracking parts, tools and consumables, wireless barcode readers, remote sensing of critical process parameters, mobile telephony, door openers, emergency communication, and general factory Wi-Fi for internet connectivity. In addition, devices not directly associated with the manufacturing process such as microwave ovens and mobile telephone hot spots must be included when designing a factory wireless system. As useful as wireless communications is, it must be recognized that spectrum is limited and there must be judicious choices about when it should be used, and when wired connections are preferable.

In general terms, wireless (as with any upgrade to a factory or enterprise system) should satisfy a requirement related to quality, reliability, efficiency, safety, regulation, or environment as shown in Table 4. The requirements pertain to the business enterprise which in the case of a manufacturing operation means the plant or factory. A wireless deployment should be designed to satisfy one of the key business concerns listed.

Table 4. Purposes for initiating a wireless systems deployment

• Functionality - Is wireless required to achieve an aspect of function within the factory operation? For example, does the factory require a mobility to achieve a goal?
• Reliability - Is reliability of the production line improved? The ability to manufacture products, parts or assemblies which conform to the engineering definition, and can demonstrate conformity.
• Safety - Are people or equipment made safer? The ability of employees to perform their jobs free from recognized hazards including falls, hazardous energy, confined space, ergonomics, and hazardous materials, and being able to demonstrate compliance with all safety regulations.
• Efficiency - The ability to meet target costs and continue forever to reduce unit production costs.
• Quality - The ability to manufacture parts and assemblies which conform to the engineering definition, and be able to demonstrate conformity.
• Environment - The ability to demonstrate compliance with applicable government regulations at the city, county, state, and federal level.

Reprinted from "Guide to Industrial Wireless Systems Deployments" by the National Institute of Standards and Technology. Get your copy here.

Analynk A75x RF Industrial Wireless DIN System

Analynk A75x

The Anaynk A75x series offers simplicity and reliability in a point to point, multipoint or wireless mesh system. One A753 transmitter can communicate with multiple A750 receivers for redundancy. A repeater can be added simply by placing in between a transmitter and receiver, no programming is required. Three radio options are available: long range 900MHz 1W, 900MHz 50mW and 2.4GHz 63mW. In addition to transmission of the industry standard 4-20mA, our transmitters can directly process thermocouples, RTD and switch states. Up to 32 inputs may be transmitted with one transmitter when the A753 is paired with our A16000 expansion module.

MODEL NUMBERS:

• A750 Receiver
• A750-Mod (RS232/485)
• A753 Transmitter
• A759 Repeater
• A753-PL Transmitter (pulse)
• A750-PL Reciever (pulse)
• A753-LP Transmitter (900MHz 50mW)
• A750-LP Receiver (900MHz 50mW)

FEATURES:

• 35mm DIN rail mount
• Standard 1W long range output, optional 50mW & 63mW
• Removable 2.0dBi dipole antenna
• DIP switch selectable channels
• Signal Strength indicator
• Repeaters available
• No software required
• Factory configured for your application

APPLICATIONS:

• Remote 4-20mA installation
• Redundant 4-20mA outputs
• Temperature monitoring
• Tank level monitoring
• Remote switch monitor
• Pulse transmission
• Remote alarms
• Rotating devices (e.g. kilns)
• Temporary 4-20mA

For more information, contact Analynk Wireless by visiting https://analynk.com or by calling (614) 755-5091.

Glossary of Terms in Wireless Networks in Process Control

Below is a list of terminology, abbreviations, and acronyms used in wireless network technology applied to process control.

• 6LoWPAN
• IPv6 Low power Wireless Personal Area Networks
• ARPA 
• Advanced Research Projects Agency 
• ARUBA
• Refers to Aruba Wireless Networks, now a Hewlett Packard Enterprise company.
• BLIP 
• Berkeley Low-power IP stack
• CAP 
• Contention Access Period
• CFP 
• Contention Free Period
• CISCO
• A company that develops, manufactures and sells networking equipment.
• CSMA-CA 
• Carrier Sense Multiple Access with Collision Avoidance
• DAO 
• Destination Advertisement Objects
• DIO 
• DAG Information Object
• DIS 
• DAG Information Solicitation
• DODAG 
• Destination Oriented Directed Acyclic Graph 
• DSN 
• Distributed Sensor Network
• ETX 
• Expected Transmission count
• GTS 
• Guaranteed Time Slot
• HBN 
• Hydrobionet
• ICMP 
• Internet Control Message Protocol
• LLN 
• Low power Lossy Networks
• MAC 
• Media Access Control
• MBR 
• Membrane Bioreactor
• MEM 
• Micro electromechanical
• MERU
• Refers to Meru Networks, a supplier of wireless local area networks (WLANs).
• MOTOROLA
• A company that designed and sold wireless network equipment.
• MRHOF 
• Minimum Rank Objective Function with Hysteresis
• NCS 
• Network Controlled System 
• OF 
• Objective Functions
• OS 
• Operating System
• PID 
• Proportional-integral-derivative controller
• PRR 
• Packet Reception Ratio
• REPEATER
• Device that takes an existing signal from a wireless router or wireless access point for rebroadcasting.
• RPL 
• Routing Protocol for Low-Power and Lossy Networks 
• RSSI 
• Received Signal Strength Indication
• WBN 
• Wireless Biosensor & Actuator Network 
• WIFI
• Technology for radio wireless local area networking of devices based on the IEEE 802.11 standards.
• WINS 
• Wireless Integrated Network Sensors
• WIRELESS ACCESS POINT
•  A networking device that allows a Wi-Fi device to connect to a wired network to create a second network.
• WSN 
• Wireless Sensor Network
• ZIGBEE 
• Popular, low-cost, low-power wireless mesh networking standard.
• Z-WAVE 
• Tightly controlled mesh network that caters to the smart home and smart building space.

Happy 4th of July from Analynk!

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