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Communications Software and Factory Automation Systems

One of the most important components of a factory automation system is the communications software that connects the system’s computers to the programmable logic controllers that do all of the work. Without an efficient and reliable communication link, the automation system or inspection system can fail.

Arde Kirka is the project manager for Megawin in San Diego; his company develops custom supervisory control and data acquisition systems and human-machine interface software for many different applications, including automated assembly, conveyor systems, storage and retrieval systems, and plastic molding. Kirka knows that communication software is often overlooked by his customers, but without good communications, an automation system will fall apart. He also says that, in addition to supporting all the correct protocols, the software must operate reliably every single day.

Microsoft’s Visual Studio development tools, which Kirka uses, are a widely used platform for creating Internet of Things applications. The PLC communication drivers from CimQuest INGear—Industrial Networking Gear—are plug-in libraries that provide a direct communication link connecting Microsoft Visual Studio to the factory floor without the need for third-party components. This enables Visual Studio to be used to craft custom Industrial IoT solutions for virtually any industry sector needing access to valuable PLC data.

In addition to custom systems, Megawin offers a product called ScadaPush—a monitoring and control system that allows users to remotely communicate with plant control equipment and SCADA software. With ScadaPush, operators, engineers and managers are notified of alarms and events that affect the operation of a factory automation system. They can also simultaneously access real-time and historical data, alarms and events so that they can make the appropriate decisions to keep the system up and running.

As shown in Figure 1, ScadaPush consists of hardware, called the appliance, a ruggedized Windows computer, and an app that runs on Apple or Android smartphones and tablets. The appliance connects to the automation system’s local area network and securely communicates via the cloud with the remote app. The appliance supports a number of different data acquisition protocols, including Trio Native, Modbus RTU/ASCII, Modbus TCP, GE-EGD/SRTP, Allen-Bradley CIP and EtherNet/IP. To communicate with the PLCs, the appliance uses INGear driver software.

According to Kirka, being able to purchase communications software that supports a variety of PLCs was very important for this particular product. ScadaPush has to support a wide variety of PLCs—whatever the customer already has installed. One customer might be using Allen-Bradley PLCs, while the next customer might be using a combination of Siemens and GE PLCs. Since each installation has its own unique communications requirements, it has to be easily configurable to meet the customer’s needs.

Kirka had considered writing his own communications software, but decided against it. “Writing PLC interfaces is not a trivial task,” he said. “You might have a team of two or three developers working on a driver, and even then, when you finish, your driver might not support all of the features of that PLC.”

He also pointed out that PLC manufacturers are continually fixing bugs and adding features to their PLCs, meaning that drivers developed in-house can quickly become obsolete. What this means is that supporting your own drivers can become a very time-consuming and expensive proposition.

Instead, Kirka relies on INGear drivers in his custom projects and the ScadaPush product. The drivers he purchases are guaranteed to be kept up to date and, if there ever is a problem, he can get support from the company. For a low, yearly maintenance fee he can get updates to the communications when they’re available, and he can devote his development efforts to the control or automation system that he’s developing for his customers. “Since CimQuest INGear drivers are available for the most widely used PLCs and work so well,” Kirka noted, “it would be crazy for me to develop my own communications software.”

Another company for whom PLC communications software is vitally important is Integro Technologies in Salisbury, N.C., which makes a variety of optical inspection systems to detect defects in containers, glass jars, round disks, cylindrical bushings, copper fittings and even tires. Most of these inspection systems use a PLC to control the machinery.

The Tire Guardian, shown in Figure 2, uses a PLC to move a tire into and out of the inspection system and gather inspection data. The system, which has a 15-second cycle time, projects a laser light sidewall of a rotating automobile tire and, using a profile sensor, digitizes the circumferential band that contains the Department of Transportation code, mold code, E-mark code and other molded-in features. The system also verifies that the tire is assembled properly on the rim and inspects the tire for deformities. Once an inspection is complete, the system displays the data on a computer screen, records and analyzes the digitized data, and decides whether to accept or reject the assembly.

According to Pat LaFerriere, Integro’s applications engineering manager, getting the inspection information from the plant floor to the executives is what’s important in his applications. That’s one of the reasons he also uses INGear software to handle the communications with the PLCs in Integro’s inspection systems. The CimQuest INGear drivers that he uses are extremely reliable and much cheaper than the drivers available from the PLC manufacturers themselves. Instead of paying for a runtime license for each individual PLC, Integro purchases a one-time developer’s license, which allows the company to develop software for as many PLCs as they want.

Another factor that sold LaFerriere on INGear software is the support. He considered developing the communications software himself and using open-source software, but decided that trying to support the software himself would be too expensive and that support for open-source software is nearly non-existent. “When we need PLC software support, we simply call CimQuest INGear, and we usually have an answer within 30 minutes,” he said.

Communications software holds a factory automation system or inspection system together and allows users to make full use of its capabilities. Both Megawin and Integro Technologies rely on INGear software to provide this functionality for their customers. They both have found that, in terms of cost, reliability and support, using INGear driver software just makes the most sense for them.

 
 
 
 
 
 
source: automationworld.com/industrial-internet-things/communications-key-automation-and-inspection-applications