Address industrial automation challenges with a new generation of PLC hardware
PLC is bridged by gateways. (See, ‘How to Connect Legacy Factory Automation Systems to Industry 4.0 without Disruption’.)
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).
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.
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 Figure 4: PLCnext PLCs use the Linux operating system and support legacy languages defined under IEC 61131-3, plus higher-level lang uages. Image source: Phoenix Contact
Figure 2: Industrial Ethernet forms the communication backbone of the modern factory. Image source: Phoenix Contact
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
IEC 61131-3
Task 1
C/C++
IEC 61131-3
MATLAB
C/C++
Task 2
Figure 3: PLCnext features task handling that enables program routines from different sources to run as legacy PLC code. Image source: Phoenix Contact
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