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DO Supply is a global leader in replacement parts for industrial automation equipment. Our mission is to elevate the standard of expert support, speed, and reliability for your need-it-now automation replacement and repair needs. Whether it's PLCs, drives, motors, HMIs, or more, you can count on us for the best service and fastest solutions.
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A new installation is not the same as a retrofit project. The selection logic for a ControlLogix processor must take into consideration elements that are absent from a greenfield project, and the risks and constraints are different. A processor must fit into a panel sized for a PLC-5 or SLC 500 chassis, communicate with devices never intended for EtherNet/IP, coexist with existing wiring, and be maintainable by a team that has worked on RSLogix 500 for years. A predetermined set of technical criteria must be followed to make the proper choice. That approach is covered from the start in this article. The first task on any ControlLogix retrofit is documenting the full scale of the legacy system, not just the I/O count, but everything the existing controller manages. A practical first pass is to group the 5580 processors by memory class: 1756-L81E for smaller systems, 1756-L82E or 1756-L83E for moderate retrofits, and 1756-L84E or 1756-L85E for larger PLC-5 migrations, high tag counts...
To the untrained eye, wiring a motor to an AC drive, more commonly known as a variable frequency drive, may seem like a simple job of plugging the motor in and routing the wiring to make it look clean. The length of the wires might not even be a concern, because in an ideal world with ideal resistance, it wouldn’t. The problem is that we live in a less-than-ideal world, and the rules of physics are nonnegotiable. Whether it’s traces on a PCB or wires during a motor install, the longer the connection point, the higher the resistance, heat buildup, and voltage drop. This matters more than you might expect when it comes to installing AC drives. Before getting into it, if you would like to familiarize yourself with how an AC drive works, check out this article here ! The inherent design of an AC drive is to output fast voltage pulses rather than a clean sine wave. Each time the AC drive switches, a voltage pulse travels down the motor cable to the motor. With a shorter cable, the pulse...
Choosing the right PLC is one of the most important decisions in an automation or infrastructure project. A well-designed PLC can help minimize commissioning time, reduce stability problems during long-term operation, and lower maintenance costs. In energy-intensive applications, PLCs do more than handle basic logic. They may also support energy optimization, multi-VFD coordination, system monitoring, and long-term lifecycle reliability. The system requirements should drive the PLC selection, not the brand name alone. Start by determining how many I/O points the application requires. A small machine may only need a few dozen I/O points, while a tunnel, pump station, or utility system may require hundreds or thousands across ventilation, drainage, lighting, monitoring, and safety-related equipment. In larger systems, distributed I/O, expansion capacity, remote communication, and reliable backplane or network performance become major selection factors. For applications tied into utility...