Select the PLC modules

Select the PLC modules The first step in selecting the PLC modules is to analyze the technical requirements of the application. In most cases this analysis will guide us in selecting the PLC and the I/Os. The next step will be to do different considerations that affect the total cost of the automation solution. In

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Input/Output Architectures

Input/Output Architecture in the control system We will give an overview of most common input/output architectures in a control system, depending on whether the priority is “Safety” or “Availability“. 1-Architectures of Inputs The following image shows the most common configurations. The letter “D” in yellow stands for “Diagnosis” and usually is associated with the Safety

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Relay Redundant System

Relay Redundant System Let’s see a simple example of how we can increase the safety of our design using conventional electromechanical relays. Suppose we have a high pressure steam line with three safety pressure switches wired to an intermediate relay. We also make a wired 2 out of 3 logic, so that the circuit is

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Availability versus Safety

Availability versus Safety This is an important point to be considered when designing a control system with a programmable logic controller. The analysis must be performed with all the elements involved: the PLC, field instruments, valves, motors, dampers, etc. In addition, it is essential to analyze the process or machine. The design will be very

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What’s a safety PLC?

What is a safety PLC? Let’s try to explain it in a simple way for non-experts. The fundamental difference with a general purpose PLC is summed up in one word “Diagnosis”. In addition, there are differences in terms of internal architecture, software and firmware, and certification for applications where compliance with a certain SIL level

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Why range 4 – 20 mA

Why range 4 – 20 mA? Since a lot of years the use of 4-20 mA standard range has been popularized because it has many advantages that we are going to discuss in this article. At the end you will understand why we use this range. Many of its advantages are the consequence of raising

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