Address Industrial Automation Challenges with a New Generation of PLC Hardware
Automation founded on the Industrial Internet of Things (IIoT) promises faster time-to-market, improved productivity, greater safety, lower costs, and higher quality. That said, there are still obstacles. Legacy systems that are difficult to upgrade, overly conservative engineering departments, closed systems, and a lack of specialist knowledge are some of the problems that are holding back the Industry 4.0 revolution.
While suitable standards-based technologies provide the backbone of the connected factory, many legacy, or “workhorse,” programmable logic controller (PLC) hardware and software have limited capabilities. This makes it challenging for engineers to quickly implement the factory-wide upgrades that are needed to take full advantage of the IIoT. Further complicating matters, engineers risk basing expensive factory upgrades on technology that could become outdated or unsupported as new technologies are introduced.
Lessons can be learned from other parts of the IoT, such as the smart home, where open systems, collaborative platforms, and accessible software make it easier to implement future-proof intelligent solutions. Industrial automation manufacturers are embracing this experience and knowledge.
This article briefly discusses the challenge of deploying IIoT technology and explains how advances in open systems and factory automation hardware offer solutions. The article introduces an example implementation of next-generation PLC hardware and software from Phoenix Contact and shows how it simplifies gathering data and sending it to the cloud for analysis and automated decision making.
The importance of the PLC
The mainstay of the factory is the PLC, a digital device invented in the late 1960s to replace earlier relay logic systems. PLCs are designed to work in difficult environments without fail for many years. The key to this reliability is a focus on simplicity. In the rare event that something does fail, PLCs are designed to troubleshoot and fix issues so that volume production can resume quickly.
The units comprise an input module (receiving data from digital and analog input devices such as keyboards, switches, relays, and sensors), a power supply, a programmable CPU with associated memory, and an output module to send information to connected devices (Figure 1).
Conventional PLCs are programmed using one of five languages defined by IEC 61131-3. These include Instruction List (IL), Symbolic Flowchart (SFC), Ladder Diagram (LD), Function Block Diagram (FBD), and Structured Text (ST). The most popular is LD, or ladder logic, which uses symbols to represent functions like relays, shift registers, counters, timers, and math operations. The symbols are arranged according to the desired sequence of events.
PLC makers are rapidly adapting to the progress in factory automation that has been made through the implementation of Industrial Ethernet. Industrial Ethernet is IP interoperable, is the most widely used wired networking option, and has extensive vendor support. Industrial Ethernet is characterized by rugged hardware and industrial standard software, and it is a proven and mature technology for factory automation (Figure 2). The hardware is complemented by Industrial Ethernet protocols, including Ethernet/IP, Modbus TCP, and PROFINET. Each is designed to ensure a high level of determinism for industrial automation applications. (See “Design for Rugged IoT Applications Using Industrial Ethernet-Based Power and Data Networks”.)
Many of today’s PLCs offer built-in Ethernet connectivity. For legacy devices featuring non-Ethernet interfaces, the divide between the Ethernet infrastructure and the PLC is bridged by gateways. (See, “How to Connect Legacy Factory Automation Systems to Industry 4.0 without Disruption”.)
The next generation of PLCs
A factory that uses a mix of modern and legacy systems can make it difficult for engineers to leverage the full benefits promised by Industry 4.0. However, lessons from other parts of the IoT, such as the smart home and logistics sectors, reveal that open systems, collaborative platforms, and accessible standards-based software make it easier to implement future-proof intelligent solutions.
The knowledge gained from these other sectors encourages manufacturers of PLCs and associated systems to introduce a new generation of products that operate like traditional PLCs without being constrained by the limitations of legacy hardware and software. An example of this new generation is Phoenix Contact’s PLCnext Control technology.
From a software perspective, a product such as the Phoenix Contact 1069208 PLCnext controller represents a significant move toward the open solutions that are starting to dominate other areas of the IoT. For example, PLCnext is compatible with a wide range of software, so innovative factory automation apps can be easily downloaded from the Internet and installed on the PLC, like apps on a smartphone.
PLCnext uses the Linux operating system (OS). It can still be programmed using the languages defined under IEC 61131-3, but Linux makes it easy for engineers to program the PLC using the higher-level languages C++, C#, Java, Python, and Simulink. These simple-to-use languages make modern factory automation accessible to a much wider cohort of engineers. In addition, PLCnext features task handling that enables program routines from different sources to run as legacy PLC code, with high-level language programs automatically becoming deterministic (Figure 3).
Connectivity is through Industrial Ethernet hardware; the control system runs under the IP-interoperable PROFINET protocol and uses the PROFICLOUD IoT platform for cloud computing support. The PLC also supports other open-standard protocols such as http, https, FTP, SNTP, SNMP, SMTP, SQL, MySQL, and DCP.
The hardware is based on an Intel Atom microprocessor running at 1.3 gigahertz (GHz). The PLC features 1 gigabyte (Gbyte) of flash memory and 2048 megabytes (Mbytes) of RAM. The IEC 61131 runtime system has 12 Mbytes of program memory and 32 Mbytes of program data storage. The unit can support up to 63 local bus devices and requires a 24 volt supply with a maximum current draw of 504 milliamps (mA) (Figure 4).
Phoenix Contact’s PLCnext range includes PLCs and other critical elements of an industrial automation system, such as communications modules and managed switches. Specific examples are the 2403115 communications module and the 2702981 managed network address translation (NAT) switch. The communications module adds an extra gigabit-capable Industrial Ethernet interface to the PLC. The module has an independent MAC address, offers PROFINET support, and includes electrical isolation between the Ethernet interface and the logic.
The managed switch is used for storing and forwarding Ethernet-transported information and features four Ethernet RJ45 ports, two small form-factor pluggable (SFP) ports, and two combination ports (RJ45/SFP). The switch is a PROFINET Conformance Class B product.
Improving decision making in the factory
Optimization of factory production is essential because manufacturing demands precision and repeatability. The key to ensuring high levels of precision and repeatability is process control. In the modern factory, IIoT sensors and cameras can monitor machines and measure finished components to pick up any minor deviations in the product and correct the process accordingly. Other sensors keep track of the health of machines to predict maintenance requirements before a worn machine starts to fail. Even more sensors keep track of the factory’s temperature, humidity, and air quality.
A key feature of PLCnext Control is that, unlike traditional PLCs, it can tap into this factory data. According to Phoenix Contact, it is sufficient to connect the PLC to just 3% to 5% of the system’s analog and digital inputs and outputs (I/Os) for it to be able to map the manufacturing processes comprehensively and without significant intervention.
PLCnext Control can then connect to any cloud service, including Phoenix Contact’s Proficloud.io, Amazon’s AWS, or Microsoft’s Azure. As a result, the factory system gains access to powerful computing resources to ensure that the operations management and maintenance processes run as efficiently as possible. The result is higher productivity, better product quality, and lower costs.
Getting started with PLCnext
Working with PLCnext controllers and related units is relatively straightforward. To assist in starting a PLC programming project, Phoenix Contact has introduced the 1188165 PLCnext Technology Starter Kit. The kit comprises a 2404267 PLCnext control module (PLC), a module carrier, and a choice of analog or digital modules.
To use the starter kit, the PLC and analog/digital module units must first be connected to the 24 volt DC (VDC) supply. Next, an Ethernet cable is connected between the PLC and PC and the PC’s IP address is set. Then, the IP address of the PLC is typed into a browser window on the PC. The PLC becomes operational after users log in with their username and password. Further instructions are supplied from the web-based management system. Programming of the PLC is done using the PLCnext Engineer software. The software allows an engineer to configure, diagnose, and visualize an entire automation solution.
PLCnext Engineer enables programming and configuration using the legacy languages defined under IEC 61131-3. It is also simple to program in higher-level languages such as C++ and C#. In addition to PLCnext Engineer, code can be built in other popular Integrated Development Environments (IDEs) such as Eclipse or Microsoft Visual Studio. The software can then be imported into PLCnext Engineer as a library for use with any compatible PLC (Figure 5).
A key advantage of PLCnext technology is that it allows several developers to work independently and in parallel on a single PLC program, even if they are using different programming languages. This enables fast development of complex applications and allows developers with legacy language skills and those with higher-level language skills to combine their talents.
The IIoT promises to transform the factory. However, while engineers are installing Industrial Ethernet, the full potential of factory automation is being held back by traditional PLCs that offer limited connectivity and dated software. PLCnext technology from Phoenix Contact is based on open systems, collaborative platforms, and accessible software. It can combine routines coded in legacy languages with those written in higher-level languages to open industrial automation to future-proof solutions with enhanced productivity, higher yields, better product quality, and lower costs.
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