What are the key features to consider when selecting a PLC for industrial automation?

To select a PLC for a project depends on the number of input and output to be used, to correspond to the number of input and output terminals for either digital or analog systems projects. The PLC power supply, CPU and the memory space, type of programming language to be used and communication and the environmental consideration -Ingress Protection.

Here's what to consider: Operating Temperature: PLCs should function reliably within the expected temperature range of your application environment. Vibration and Shock Resistance: Select a PLC that can withstand vibrations and shocks common in industrial settings to prevent malfunctions. Electromagnetic Interference (EMI): Industrial environments can have significant EMI. Choose a PLC with proper shielding and filtering to ensure immunity to electrical noise. Conformal Coating: For applications with exposure to moisture, dust, or contaminants, a PLC with conformal coating on its circuit boards provides an extra layer of protection.

Here's a breakdown of the key aspects of I/O configuration: I/O Modules: PLCs typically have a limited number of built-in I/O points. I/O modules are used to expand the number of I/O points by connecting them to the PLC's backplane or communication network. I/O Addressing: Each I/O point has a unique address that the PLC program uses to access its data. Proper I/O addressing is crucial for the PLC to interact with the correct devices. I/O Configuration Software: PLC programming software usually includes a dedicated module for configuring I/O points. This software allows you to define the type, address, and other properties of each I/O point.

Here's a look at some key communication options for PLCs: * Serial Communication Protocols: These protocols, like RS232 and RS485, are commonly used for point-to-point communication between PLCs and other devices over short distances. * Ethernet-Based Protocols: Industrial Ethernet protocols like Ethernet/IP and Modbus TCP/IP enable high-speed communication over Ethernet networks, facilitating integration with various devices and SCADA systems. * Fieldbus Networks: These specialized networks, such as Profibus and DeviceNet, offer communication standards for industrial automation applications, often using multi-drop configurations for connecting multiple devices.

Here's a closer look at what programming flexibility entails: * Supported Programming Languages: Modern PLCs typically support a variety of programming languages, including ladder logic (a relay logic-based graphical language), structured text (a text-based language similar to C), and function block programming (utilizing pre-defined blocks for common functions). * Ease of Use: The chosen PLC's programming environment should be user-friendly, with intuitive software and clear documentation to simplify program development, debugging, and maintenance.

Raw clock speed (MHz or GHz) isn't the sole metric. Here's a breakdown of what to consider: * Instruction Cycle Time: This is the time it takes the PLC to execute a single program instruction. It's a more relevant measure of processing speed for PLCs than clock speed. * Program Complexity: The complexity of your control program will influence the processing requirements. More complex programs with many calculations or data manipulations demand faster instruction cycle times. * Real-Time Performance: For applications requiring strict timing control, select a PLC with deterministic performance, meaning it can consistently execute a scan cycle within a predictable timeframe.

Um ponto que vale a pena ressaltar é o quão intuitivo é utilizar e navegar na interface deste PLC. Muitos funcionários que estão no começo da carreira ou que não estão habituados com certa marca específica podem ter muita dificuldade para aprender com um PLC onde a navegação e interface são muito complexas.

One thing I have found useful is consideration of future trends, most PLC series are being scraped out by manufacturers. Hence the spare parts may not be available sooner or later. Just ensure that you understand the direction the brand manufacturer is taking as far as technology enhancement is concerned. I have been invited to offer troubleshooting and maintenance services for some PLC that are out phased by the manufacturer, convincing clients to make changes some times may make them lose trust. Future trends like integration of IoT is quite necessary.