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How to Connect to Allen Bradley Ethernet-Enabled Devices?

If you have come across a similar situation where you cannot connect Ethernet to Allen Bradley Controller, then you have come to the right place. One of the major reasons why people fail to connect to Allen Bradley Ethernet-enabled devices is probably because their system’s IP address has not been properly configured or the network adapter of the PC is set up for DHCP. In general, network adapters of computers are set up for DHCP by default and they need to stay the same so that they can be connected to the majority of companies and home-based routers.

ALLEN BRADLEY PLC is an industrial computer control system that will enable you to utilize the majority of the industrial processes. Your system’s network adapter has to be set up in a way that it has a static IP address so that you can connect your system to Allen Bradley Ethernet-enabled devices. Let’s take a rundown at things and how you have to set up the PC and the device. Starting with the PC first,

  • Ensure that the Allen Bradley device is able to communicate over IP or Ethernet. If the cable has properly fitted into the port, in no way does that mean that you are using the correct one? Even the wrong ones can fit into the port appropriately and a lot of Allen Bradley devices use RS485 ports which are the same as the ones in Ethernet cables.
  • Ensure that all the devices are powered up properly and the cables are well-connected.
  • Ensure that the correct software is installed on your computer to enable connectivity and communication with Allen Bradley Controllers and Drivers.
  • Once everything is in place, configure the IP address and subnet for your computer. This is where the problem lies, as already stated above most PCs are set up for DHCP by default so you have to make sure that they have a static IP address.

1How to set a static IP address?

Given below are the steps you can follow if you want to set a static IP address on your system:

  • Click on the start menu on your windows system and select “Control panel.”
  • After that, select the option “Network and Sharing centre.”
  • Do you find the option “change adapter settings”? Click on it.
  • Select “Properties” once you right click on “Local Area Connection.”
  • Now, click on the option “Internet Protocol Version 4” and then select “Properties.”
  • You will see two options now- choose the one that says “Use the following IP address:” Here you can set the IP address but, if you want to change the settings back to the company’s network then choose the other option.
  • Once you are done setting the IP address and subnet then click on “OK”.
  • You will see a “Local Area Connection” window, select OK again.

That’s it! Your IP address has been set up on your system and it has been configured. Now, you can successfully connect to Allen Bradley Ethernet-enabled devices.

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What is Field Bus and what are the Foundation Fieldbus basics?

Before the introduction of Foundation Fieldbus, the gateway to the industrial automation started with parallel wiring, where the devices were connected independently with the rule and control level.   

However, with the increased levels of automation, the number of participants also increased. This led to a high wiring expenditure. Hence, it was extensively replaced by economical and faster Fieldbus systems.

Foundation Fieldbus systems are targeted for fieldbusplatforms using advanced as well as primary regulatory control, along with some of the discrete commands associated with those functions. The technology was previously used in the process industries; however, with recent advancements, Foundation Fieldbus are now being applied in power plants as well.  

Definition of Fieldbus

Field and Bus make Fieldbus. A field is a geographically limited area. In an engineering world, it is intellection of the plant levels. Bus, on the other hand, is a set of a standard line that electrically links multiple circuits for transferring information.  

The idea behind Fieldbus is to eliminate any point-to-point links between the field devices like actuators and sensors and their controllers by a single digital connection on which all the information is communicated consecutively in serial order and multiplexed over time.  

In most cases, the Fieldbus transfers the information in small packets in a sequential manner. The subsequent transmission of information decreases the total required number of connecting lines over greater distances than that of parallel transfers.  

Examples of Fieldbuses

  • Interbus– it has a transmission rate of up to 2 Mbps, which is characterized by high transmission security and constant, but short cycle time.
  • Profibus– it is used in manufacturing automation and engineering industries. It has a transmission rate between 9.6 kbps and 500 kbps. It uses a hierarchical structure with the actuators and sensors levels.

Within the process automation environment, there are two related applications of Foundation Fieldbus. They use different communication speeds and physical media.

  • The H1 segment operates at 31.25 kbit/s. H1 segments are usually used for connecting host systems and field devices. As compared to standard twisted-pair wiring, H1 segment offers more power and communication in both intrinsic and conventional safety applications. It is the most popular Foundation Fieldbus application.
  • High-Speed Ethernet (HSE) operates at 100/1000 Mbit/s and is used for connecting gateways, host systems, subsystems, and linking devices. However, HSE doesn’t provide power over the cable, for now.  

Benefits of Foundation Fieldbus

  • Multidrop wiring
  • Multivariable instruments
  • New types of information
  • Two-way communication
  • Control in the field
  • Interchangeability- devices can be functionally interchanged without changing the functionality
  • Interoperability- devices can communicate with each other while performing in multi-vendor environments with ease


What does this mean?

Considering the mentioned benefits of Foundation Fieldbus, there are plenty of reasons why it is implemented in many automation industries. So of them are as follows:

  • Speed – Systems can be installed and organized more quickly
  • Reliability – Short signal paths mean increased availability and reliability  
  • Interference reliability – Increased protection against interference  
  • Uniformity – The use of unified connection technology and standardized bus protocols enable the use of different devices from different manufacturers
  • Flexibility – Modifications and expansions can be implemented quickly with ease

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The Difference Between Profibus And Profinet

Profibus and Profinet are two terms that are often confused with each other, both of them being field networks part of industrial automation protocols. However, there are significant differences between the two in various aspects and for the same reason are used for different purposes in industries.

In order to clearly understand their functioning and application of the two, it is important to first get a good grasp of the basics.

The basics

Profibus which is the acronym for Process Field Bus is basically a standard for fieldbus communication used in automation technology. Profinet on the other hand, which is acronym for Process Field Net is a standard for internet communication over industrial Ethernet.
As they are both very popular and highly sought after automation protocols created by the same organization, they do share a number of similarities. They are both created and maintained by Profibus and Profinet International.
However, Profinet comparatively has extra advanced capabilities that facilitate a faster and a more flexible field of communication within a network.

ethernet_profinet_graphicThey share the same application profiles; which essentially implies that they have similar guidelines followed by different categories of devices within a network, regarding their use of Profibus and Profinet data during communication. These profiles enable smooth planning and functioning of the automation systems and devices.

Other than that they are also very similar in terms of their engineering concepts and they use General Station Description files to define the hardware for each device. The file type however is different.

In simple terms Profibus is a classic and traditional automation protocol based on serial communication while Profinet is a newer enhanced automation protocol based on Industrial Ethernet.

Significant points of differences

Profibus and Profinet use GSD files for define the hardware for various devices. But as mentioned before, the difference lies in the type of file being used. Profibus uses ASCII files whereas Profinet uses XML files.

In terms of their base field, Profinet made the move from RS-485 to Ethernet to become more efficient and ubiquitous. It is a more adaptable and modern technology that helps organizations future-proof their processes.
Besides that, being based on industrial Ethernet, Profinet also enjoys a higher bandwidth, a larger size of message and unlimited amounts of address space. Separate controllers attached to the network may have to adhere to certain limitations in terms of address space, depending on their memory capacity and processor capabilities though.


Other than that, Profinet is faster than Profibus because of the provider/consumer model that it uses, where any node in the network is allowed to communicate at any given time. Hence, there is no delay in information exchange.
Besides that, Ethernet networks are generally switched networks that are practically devoid of network collisions.
Profibus uses a master/slave approach rather than a provider/ consumer model where the master is usually in charge of the entire network and the nodes are allowed to communicate only when prompted.

Usually industrial enterprises are required to deploy separate gateways in order to communicate with other networks. However, with Profinet, it creates its own proxies for translation and data exchange between two different networks and unlike an ordinary gateway they are defined in an open standard.
In case of Profibus, there is a facility for wireless transmission of messages; however, it requires similar based proprietary radios at both ends.
As Profinet works on standard Ethernet, it can easily use WiFi or Bluetooth for wireless transmission.

Even though Profinet is an enhanced and more versatile version of Profibus, it does not mean that the former can be used across industries regardless of the processes. It is important to study the field of automation and choose the protocol accordingly.

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What is The ControlNet Network?

ControlNet is an open-sourced industrial network protocol. It is best suited for industrial automation applications. Interestingly, it is also known as a Fieldbus. This industrial network protocol caters to the demands of high-throughput applications required for automation. Another exciting feature of this industrial network protocol lies in the fact that it facilitates processes of discrete claims. It is based on the token-passing bus control network interface, which is of great use in industrial automation. In this context, it is essential to note that ControlNet uses the Common Industrial Protocol to facilitate interconnection between various levels of the Open Systems Interaction (OSI). There are seven layers of OSI, namely data link, network, physical, session, presentation, transport, and application.

The Design of ControlNet

ControlNet is designed in such a manner that it provides high-speed control and reliable data transfer by the usage of programming. This, in, turn, sets the logic to a specific timing over the network and facilitates faster data transmission. The ControlNet Network comprises of devices like the I/O chassis, programmable logic controllers, personal computers as well as drivers. In this context, it is vital here to note that ControlNet has a data transfer rate of around 5Mbps. This ensures that the data transmission within the industrial architecture always stays relevant.

The ControlNet Connectors that Help in Industrial Automation

It is important here to note that ControlNet cables are the RG-6 coaxial cable types with the BNC connectors. The connectors of BNC can either comprise of a twist on and locking type. It also sports a rugged design that is of the threaded screw type. This screw threaded design helps you to make sure that it can withstand harsher environments.

The ControlNet Cables That Are Used in the Network

ControlNet provides you the liberty to select the cable types. The cable types comprise of direct burial or flexible nature. Moreover, they are also designed in such a manner that they can be used in harsher environments. On the other hand, there are various applications for ControlNet that need longer distances and also use optical fiber in the cabling. It is important here to note that it can support a maximum number of 99 nodes on the network. Moreover, the repeaters also do not use the node numbers. This is the reason that they don’t count these nodes as a part of the maximum amount.

The ControlNet Data Link Layer

In ControlNet, the nodes are assigned with a MAC ID address 1 to 99. Moreover, each node also knows the address of the predecessor and the successor. Each node that is present in the ControlNet interface has a scheduled time, which is also known as a token. In the ControlNet network, only one node can be transmitted at a time which would eventually prevent the data collisions from taking dangerous propositions.

If ControlNet is set up correctly, it can be very stable and reliable. Moreover, over a longer period, it requires lesser maintenance when compared to other industrial automation networks.  


What is a protocol converter in networking?


In networking, a protocol converter is a program or a device that converts from one protocol to another allowing inter-dependability between systems or devices that use dissenting protocols. Essentially, communication protocols are the rules that define how the data passing through a system are to be processed and transmitted. If two or more systems or devices don’t use the same protocol, then they cannot understand (communicate with) each other; thus the need for a protocol converter.

In simple words, a protocol converter converts from protocol to another in order to permit the systems to achieve interoperability.

The protocols are software installed on routers that transfer commands from one system to another. The process incorporates conversion of data, commands, their encoding, demonstration and enclosing to accomplish the transformation.  

There is a whole host of protocols used in numerous fields of networking that includes events and time synchronization, conversion of data messages, major protocol translation messages involve commands, AMR, automation, utilities, transmission and distribution, power generation, oil and gas, and remote monitoring applications.

A protocol converter works by utilizing an internal master protocol for communicating with the external devices. The data collected is then used for updating the converter’s internal database. There are numerous physical mediums used for communication on protocol-X and Y including the Ethernet, RS-232, and RS-485 among others.

Types of protocol converters

There are primarily two types of protocol converters used in networking. They are:

  1. Software Protocol Converters
  2. Hardware Protocol Converters

Choosing a protocol converter

When choosing a protocol converter, it is critical to go for a converter that best suits your communication and application setup. The following are the three factors to consider when choosing a protocol converter.

  • Total number of connections: Some protocol converters have only single connections, while others have as many as 32 connections including multiple serial ports.
  • Connectivity protocol: The protocol converter must support the protocol used by your network whether Ethernet, RS-232, RS-422 or RS-485.
  • Baud Rate: The protocol converter you choose must have high baud rates for high performance.

Applications of a protocol converter

The applications of a protocol converter differ from industry to industry. Depending on the protocols, it can be a software converter or a hardware converter. Some of the key applications of a protocol converter include building automation, vehicle automation applications, automatic meter reading, process automation, industrial automation, and substation automation.

In situations, where a signal from the system or device is inept at coexisting with the protocols used by the network management system or building management system, a protocol converter is best suited.

A protocol converter can receive up to a maximum of 1024 inputs over 32 modules, allowing for flexible integration with multiple alarm and management systems using a single device. On the other hand, the protocol converters are used with fiber media converters, PDH multiplexes, PCI Express network cards, DWDM equipment, CWDM, and switches.

Final Words

All in all, protocol converters play an essential role in telecommunication and networking applications.  

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RSLinx: Essentials to Know

rslinx1Communication software has come a long way from basic emails and chat systems now. Advanced technologies these days provide more than just a mechanism for different systems and users to exchange files and terminal emulators among themselves.

As devices are getting smarter by the day, there is indeed a need for more intelligent mediums facilitating communication between the same.

RSLinx is one such communication software developed by Rockwell Automation.

What is RSLinx?

RSLinx is basically a windows-based communication software or server often used to interface and facilitate seamless communication among all of the Rockwell industrial control and automation hardware. The RSLinx Classic, which is one of the most popular versions of RSLinx, also provides plant-floor device connectivity in automation industries for a wide range of Rockwell software applications like RSView 32, Factory Talk View Site Edition and Factory Talk Transaction Manager as well.

It comes in a variety of types with minor variations in terms of their capabilities, inclusions and in turn their usability. Some of them are:

  • RSLinx-OEM – this provides DDE capability meant for Rockwell DDE enabled software.
  • RSLinx Professional – this again provides DDE capability to DDE enabled software
  • RSLinx Lite – this acts as a PLC programming software communication interface
  • RSLinx SDK – this is a complete Software Development Kit that includes the OEM version as well.

RSLinx makes use of OPC or DDE to provide connectivity for client applications, although OPC is the preferred and more commonly used interface for data acquisition applications as it is considered as a factory standard for communications.

RSLinx comes with a number of major benefits including a very user-friendly graphical interface, multiple data value viewing options and ladder viewers to facilitate viewing ladder codes. It can thus be used to communicate from anywhere to anywhere.

What is RSLogix?

RSLogix; an RSLogix client, is the programming software for which RSLinx facilitates communication. It is a design and configuration software developed based on the Rockwell Automation Integrated Architecture. It supports a wide range of applications from discrete to process to motion to safety to batch and drive based applications.

It serves as a single control platform for any kind of automation discipline in industries as it provides a common engine and development environment. It features unique capabilities like ladder logic, structured text, sequential function chart editors and function block diagrams. It also comes with troubleshooting tools1 and advanced diagnostics.

Apart from that it also has an easy-to-use IEC 61131-3 compliant interface along with a holistic instruction set that caters to a wide array of applications. Put together with the Integrated Architecture System it helps industries to enjoy plant-wide optimization of processes in an efficient and effective manner.

What is RSLinx Gateway?

The RSLinx Gateway basically helps extend the communication network throughout an organization. It enables RSLinx clients such as the RSLogix 5000 or RSLogix 500 to go online and connect with processors like the PLC-5, SLC-5, MicroLogic or ControlLogix residing on a particular control network over the Ethernet.

RSLinx Gateway is also used to optimize communication between various OPC clients and other devices on the same floor in industries. It facilitates hassle-free communication by consolidating multiple data requests from different clients, into one single request which is forwarded to the controller. This essentially helps in reducing the overall network traffic and data load on the end controller.

This is beneficial in terms of cost-reduction as well, as it eliminates the need for an RSLinx copy to be kept active on each client machine.

How do I download RSLinx?

Owing to recent design changes on the Rockwell Automation website, the free version of RSLinx is a little difficult to find. The direct link to the download used to be available on the first page of results when you searched for “micrologix downloads” on the main page of Rockwell Automation. But it is not available anymore.

However, the link still is available on the website. All you have to do is go to the product compatibility and download centre.

–          From there click on “find downloads” and type in “RSLinx” in the search column.

–          From the list of options that show up click on RSLinx Classic Lite (free version).

–          Once you’re taken to the product page, click on the download button.

From there, all you have to do is follow instructions. If you are a first time visitor to the Rockwell Automation website or if you’re using their software for the first time, you might need to create a work-based account first.

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Everything You Need To Know About Ethernet Network Communication

ieb44tunnel1In terms of computing and networking, the Ethernet or the Local Area Network (LAN), MAN and WAN of computer systems that we use for commercial purposes or otherwise has a rich set of protocols and formatting regulations that enable a smooth network connection. It is responsible for the clear and smooth transmission of data across network devices as well as over the network connection.

In order for the Ethernet to control, monitor and regulate data being transmitted across networks, it makes use of specific technology and features including an Ethernet gateway. Let’s learn more about how the Ethernet facilitates communication across networks.

What is an Ethernet gateway?

An Ethernet gateway, sometimes called a router is basically a node or one of the communication endpoints in a computer network that uses the Internet Protocol Suite that is responsible for forwarding data packets to other networks in cases where the network protocols are similar.

In other words, a default gateway serves as a router or a forwarding host to redirect data packets, while also being a common access point to other networks. This may involve not just address changes but also completely different networking technologies with different network prefixes as well. Such gateways are called internet gateways.

Now both the internet gateway and the router or the Ethernet gateway, are nodes that connect and regulate traffic between two or more networks. But the type of networks being handled is what is different.

A Windows 2000 network that uses the TCP/IP internet protocol as its primary protocol can use a router or an Ethernet gateway to connect to the internet as it is the same primary protocol that the internet uses.

An internet gateway on the other hand would be used to connect a Windows NT network for example with a NetWare network.

How does the Ethernet gateway work?

The Ethernet gateway is always connected to two or more different data lines from different networks. It reads the destination IP addresses on data packets coming in from the data lines and determines the ultimate destination. Then it makes use of the information on its routing table or the Routing Information Base (RIB) and directs the data packet to the next network on its route or journey. RIB is basically a data table that has a list of routes to particular destination addresses and sometime even the distance information associated with these routes.

The Ethernet also makes use of Ethernet converters and serial to Ethernet converters for converting media and data signals.

What is an Ethernet converter?

An Ethernet converter also called an Ethernet media converter is basically a device that is designed to enable the communication and smooth connection between different networking media such as fibre and co-axial cables used by different networks. It usually comes in the form of a small box and typically it is used to connect fibre media coming from an optical fibre based network and a copper-based network which is more conventional.

What is a serial to Ethernet converter?

Just like the media used by different networks, the data signals across networks may also come in serial form, which need to be converted to Ethernet packets in order to be routed and processed. This job is done by serial to Ethernet converters which are also called terminal servers or device servers as they are devices that have their own IP address.

It basically is a device that converts serial RS232, RS485 or RS422 data to Ethernet packets and also Ethernet TCP/IP packets back to these serial data signals. It comes in different models that facilitate different conversions.

How does a serial to Ethernet converter work?

A serial to Ethernet converter device usually comes with driver software that you need to install on your PC. The program creates virtual COM ports within the system when the converter is connected to the system. You can see all the virtual ports created by the software on your device manager list.

When you connect a serial device to one of the hardware ports on your converter device, the peripheral gets redirected to the visual serial port of your system and is identified by your PC as a local device. The circuitry within the converter then goes about converting each of the signals to Ethernet data packets for effective communication.

Difference Between Allen Bradley And Siemens PLC

One of the biggest boons that the industrial sector of the world at large received came in the last century. We are talking about the invention of the Programmable Logic Controller (PLC) by Dick Morely back in 1969.

Ever since then, there have been many innovations in terms of functionality and hardware features for the control system and needless to say, each new one has been tough to beat. There are predominantly two giants who have had the duopoly in the manufacture of efficient PLCs for a long time now and they are Siemens and Allen Bradley.  


While each of these are established and top notch companies who have already proved the worth of their super-efficient TLCs individually, there has forever been a debate over which of these is better.

So here is a detailed comparison between the Allen Bradley and Siemens PLCs.

Before we begin, a quick word about what a PLC is.

What is a PLC?

In the simplest of terms, a Programmable Logic Controller or PLC is an industrial computer control system that allows you to get the most out of industrial processes. It helps enhance the processes while at the same time allowing you to switch up, replicate or change the processes as well quite easily.

Allen Bradley Vs. Siemens PLC

First things first, the quality and functionality of the hardware are significantly distinct. Both the AB and the Siemens PLCs work pretty much the same way and are equally reliable. The difference lies in their installation processes.

While the Allen Bradley requires you to connect the PLC to both the Allen Bradley power supply as well as the Allen Bradley rack, the Siemens one works with pretty much any 24 V DC supply of power. Also, you might need to install additional safety communication ports for Rockwell while Siemens already comes with built-in communication ports.

Another major difference is in the protocols they use. AB uses mostly native American IPs such as DeviceNet, ControlNet and EthernetIP, and also the DH+ or DH485.

At the same time, Siemens uses European native IPs such as Profibus and ASI and also serial MODBUS or MODBUS TCP/IP.

image3Coming to the interface and ease of use, AB has a more intuitive and easier user interface and it allows users to manage and control their processes even without a lot of programming knowledge. It also has excellent features like communicative abilities with third party hardware, mass production of code and even export and import of tags from Excel to scada databases.

Siemens might be a little complex for the maintenance staff that may not have a programming background.

On the flip side, Siemens offers a lot of options to program and customise the process to suit your business model.


As for the pricing aspects, Allen Bradley definitely is more expensive when compared to the Siemens PLC. However, Siemens offers standard technical support at all times at no additional costs while AB does charge you for technical support according to the amount of hardware you have installed.

That said, it would be ideal to choose one of these according to your priorities in terms of business processes.

Now if you have both Allen Bradley and Siemens devices and you want them to communicate, then you can use Equustek DL3500-MODBUS/DH+ or DL3500-MODBUS/DH485 for All Siemens that can handle uses serial MODBUS and Allen Bradley that support DH+ or DH485, or use the DL6000-MEDH+ or DL6000-MEDH485 that allow Siemens with MODBUS TCP/IP to communicate with Allen Bradley DH+ or DH485 devices.

What is FactoryTalk? What is FactoryTalk viewpoint and security?

FactoryTalkFactoryTalk services platform is a suite of services developed by Rockwell Software. It includes Alarm and Events, Activation, Security, Audit, Directory, and Live Data. FactoryTalk is not a product that can be purchased as a standalone software package. FactoryTalk is embedded in most of the products from Rockwell Software; that is, it is the prefix to the majority of the Rockwell Software’s products.

To better understand each component of FactoryTalk services, here is a brief description to give more of an understanding of the proficiencies of each module.  

  • Alarm and Events

Provides both device-based and server-based process control alarm server

  • Activation

Provides a safe software-based system for activating the products of Rockwell Software along with managing software activations

  • Security

Provides the users with a range of security services that are pre-installed in the FactoryTalk directory. The user groups and users are identical when it comes to managing them in the active directory. Moreover, they can be linked to the active directory as well. This functionality enables the users with centralized authentication and access control resulting in ‘single-user sign in’ when using FactoryTalk enabled products and services.

  • Audit

It collects messages documented by the user regarding the management, design, and operation of production. It works as a configuration management tool and a process control system asset for smooth operations.

  • Directory

The directory allows the products to share a standard address book that locates and provides access to factory-floor resources that includes graphic displays, tags, roles, and users. Using the FactoryTalk Administrative Console application, the directory can be managed.

  • Live Data

It provides with real-time data between the servers and clients. That is, it will show the connection between the PLC and the HMI server, or between a PLC and FactoryTalk Historian SE. The live data server of FactoryTalk is for Rockwell Automaton devices that allow to manage the link between OPC-DA servers and clients for non-Rockwell Automation devices.

What is FactoryTalk Viewpoint?

factory-talk-viewpointFactoryTalk Viewpoint is an extension to the PanelView Plus and the View Site Edition, which adds web server features to the FactoryTalk View project.

When Viewpoint was first implemented by Rockwell, they did so as a Silverlight browser plugin. That means FactoryTalk Viewpoint is limited to Windows devices including tablets.

Its updated version was released in 2017 that went from being a Microsoft application to an HTML 5 application. The update improved FactoryTalk Viewpoint’s compatibility with devices, operating systems, and browsers that do not support Microsoft Silverlight.

However, people using FactoryTalk Viewpoint has complained about the software being slow.  

What is FactoryTalk security?

FactoryTalk security is a primary source of authentication and authorization controls. Instead of enforcing the same controls on each system with the RSLogix application, the users are entered and managed in one location.

Moreover, the authorization is a bit coarse, meaning it can be based on multiple actions individually aligned for each system. What makes things easier is that the application supports groups for role-based access control; thus, not everybody can access the system without mentioning the role.

FactoryTalk security allows users to access the application locally or using proxy authentication. In case, if the users have arranged a separate domain, they can leverage that existing infrastructure.–photograph_848w477h.jpg×584.png

Modbus And RS485: Everything You Need To Know

In the world of industrial internet communication and networking, there are a lot of minute details that contribute towards giving us the convenience of information at our fingertips. From the type of computer network at the client end to the internet protocol to the databases being used, there are a lot of things that must come together in order to make a simple search request or process automation successful.

One such detail that plays a very important role in making exchange of information smooth and successful is the Modbus protocol along with the RS485.

These are two different but related concepts that people are often confused with. So let’s see what they are in detail.

What is Modbus and Modbus RS485?

Simply put, Modbus is basically a protocol that facilitates communication between the “master” or the host and the “slaves” or the connected devices. It enables the host to read the measures and aids in the configuration of devices.

On a basic level, the Modbus protocol facilitates communication with the help of messages that equate to simple operations necessary to read and write regular 16 bit words and binary details or registers called “coils”. The host or the master usually initiates the exchange and the slave or the device usually replies.

Hence, as is evident, the Modbus protocol literally defines the messaging structure used in the exchange of data between the host and the slaves or the devices.

It must not be confused with a medium of communication though. It forms the messaging structure alone and is not the physical medium of data exchange.

Now, in a normal stream of industrial data exchange or communication during process automation, there usually is a master which most often is a Building Automation System or a BAS, a communications gateway device, and a PLC or a software program that is running on a computer.

In order for the data exchange to happen, the host requires a medium that not only facilitates the exchange but also determines the pace.

Enter RS485.

It is basically an electrical or serial transmission standard that defines the physical level of electrical signals between the host and the slaves and also the wiring that enables the transfer of data. It is a popular standard used in data exchange as it allows the usage of several devices using the same standard on the same bus, which eliminates the need to multiply interfaces on the host while querying multiple devices.

Hence, when we say Modbus RS485, it denotes the protocol being used in process automation along with its ability to communicate effectively by the name of serial transmission standard.

On a normal case, a single multi-drop RS485 serial bus can facilitate up to 127 slave devices, which again is a good reason for its popularity.

Is Modbus the same as RS485?

The answer is no, because both of these are relative concepts that need each other in order to fulfil their purposes. Modbus defines the protocol type and RS485 defines the signal level on the protocol.

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