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.  

       

Communication 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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In 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.

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.

Coming 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.

FactoryTalk 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?

FactoryTalk 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.

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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.

A PLC which stands for Programmable Logic Controller, is basically a technology used to control automated systems in various industries. It is an important part of process automation across industries these days and they constitute simple forms of control systems that have been increasingly replacing hard wired logical relays spread out on a large scale of late.

It is similar to typical PCs in certain hardware and terminologies such as central processing units, memory and communication. However a PLC is designed to operate in more rough and rugged industrial surroundings and is also more flexible in terms of interfacing with inputs fed in as well as outputs generated.

How a PLC works

The working or functioning of a PLC is dependent on its 3 main components. As mentioned before, just like how a normal PC has a CPU, a PLC also has similar parts that decide how it functions. They are:

–          The Central Processing Unit (CPU)

–          The power supply and rack

–          The input and output section

An additional segment can be identified for a PLC considering its industry-heavy application and that is the program section.

In brief terms, PLCs work as per the following sequence:

• The input section first converts real time analogous electric signals that it receives into digital electric signals which the PLC uses with the help of certain connector rails
• The CPU then stores these digital electric signals in the PLC external memory space. The locations are called bits.
• In the next step, the programmable instructions are spelled out for the device in the form of mnemonics and symbols which are then stored in the user memory.
• Then, just like in a typical PC, the CPU extracts these programmable instructions and executes them by manipulating and processing the inputs so as to control the output devices.
• The results of the implementation get stored in the external memory space that controls the output devices

In addition to these, the CPU also performs the functions of updating input storage with changes attributable to the alterations in output content. At the same time it also performs internal functions like resetting the timer and keeping a check on the user memory.

What is PLC control?

PLC control is nothing but the control affected through the deployment of PLC automation software. From a general perspective, a PLC helps control different devices working in an industry without being too rigid with the process flow. For the same reason, it is often known as a method of “softwiring” the different devices involved in process automation.

They are known to provide this kind of flexibility without compromising on reliability and robustness. They eliminate program crashes or other mechanical level failures as well.

Moreover, as they are available in even small sizes, they are more compact and much more economical when compared to traditional control systems.

What is PLC training?

PLC training refers to the employee level skill development and training imparted in order to familiarize the concept and functioning of a PLC in any industry. As is the case with any new deployment in any industry or office, new process automation software deployment also requires the management to carry out specific training programs for the middle and lower level employees, who may be operating the system.

Additionally, PLC being an industry norm these days, there are also specialized PLC technician training programs offering professional qualification with valid certification for prospective PLC operators who may be interested in pursuing a career in the same. The program typically involves modules detailed on the basic knowledge and skills required to work with a PLC system within an industry.

 

PLC is a kind of digital computer that is utilized for the purpose of automation in the electromechanical processes in the plants. It is made for multiple outputs and inputs arrangements so that the data can be availed through the sensors, used, and the command can be issued to the actuators. When it comes to PLC, a foremost name that deserves a mention is that of the Allen-Bradley range of factory automation equipment by Rockwell Automation.

What is Allen Bradley?

Allen-Bradley is the name given to a range of factory automation equipment made by Rockwell Automation. The company deals in the manufacturing of PLC (programmable logic controllers), sensors, human-machine interfaces, safety systems and components, and many more of such high-end equipment. Allen Bradley is one of the premier PLC software manufactured by the company and adopted by the companies around the world.

What is Allen Bradley software?

The Allen Bradley software products are used to support the intelligent I/O modules, collectors, portable data, servo drives, power-flex drives, motor control centers, sensors, programmable controllers, and motors. The designs of this software ensure configuration and designing of the products such that they are able to deliver the work faster to offer accelerated content and provide value for the time through utilization of the high-end tools.

What is Allen Bradley PLC programming?

In the Allen Bradley PLC programming software, the connection between the computer and the controller is established through either Ethernet cable or serial cable. RSLogix is the name of the programming software of Allen Bradley’s PLC. Understanding this PLC software is suggested before taking any PLC training session and the basics course of PLC is based on the Allen Bradley PLC programming software. The knowledge that is acquired, thus, can be used in any PLC brand. Here are a few of the steps to set up a project on the PLC Allen Bradley using the Allen Bradley RSLogix 5000 software.

The configuration of the software

Connect with the controller using the Serial Port and start the configuration of the Serial driver. Connect the serial cable on one side and controller on another side of the PC. The next step is the configuration of a connection. In order to configure the connection, you can utilize the RSLinx Classic Lite from Rockwell Automation. RS232 DF1 Device driver is best to be used for the serial communications. After you have selected the configuration driver, the following are the steps that you need to undertake.

1. Select the RS232 DF1 Device driver from the pull-down list having the names of the driver types.
2. Select add new for adding the driver In the ‘add new’ dialog box, write the name of the driver and click on OK.
3. To specify the settings for serial port:

•   Select the option of the serial port on your workstation from the menu of Com Port. This is done to make sure that the cable is properly connected to the ports.
  Select the serial port from the pull-down menu for Devices
• Click on Auto Configure. :

The automatic configuration should be successfully initiated after this, and if it fails to do so, then you must have selected the wrong port. Check that and initiate the configuration one more time. The configuration of the I/O modules is needed for the physical modules of the project and it constitutes of the simple steps of Ladder Logic programming and Logical Continuity.

Image Sources
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