Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [plc]

Programmable Logic Controller

A Programmable Logic Controller (PLC) is mainly used in industrial applications to control production lines and its machines. It is a replacement for a large bank of relay logic.

Related reading:
An Overview of Software Languages for Programmable Logic Controllers

253 questions
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Why use PLC instead of microcontroller?

Why does everyone use PLCs in industrial environments, instead of a microcontroller based solution? For a longer task, the PLC program is as complicated as a microcontroller program. A microcontroller based solution may be more customisable, and of…
Saneesh A T
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Are there any commercially available PLC's that can compile/ download programs through an API?

My team has decided to use a PLC for controlling an industrial process that requires simple, real-time IO to external devices with minimal processing. However, we expect the exact outputs needed to vary between runs (in fact, a given run will very…
Dragonsheep
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Digital logic input with very wide input voltage range

We are developing an industrial controls product that will be used to monitor the presence or absence of voltage ranging from 5V to 480V. Since the unit will be generic and programmable, this input may be used in a variety of unpredictable…
TimH - Codidact
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Is there an open source IO-Link stack available?

I have been looking at designing a solution around an IO-link master. Does the IO-link Consortium allow for open source implentations of both the master and slave? The documents online seem to give enough info to implement at least a basic feature…
zageek
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Should cable shields be connected to earth ground, or to power supply negative?

I'm working on a PLC cabinet, and I'm wondering whether I should hook cable shields to earth ground, or to the power supply negative. I checked and the power supply DC output is isolated. There's no conductivity between earth ground and the power…
Drew
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SPI signal noisy when contactor switches

I created a Raspberry Pico based PLC board which worked perfectly alone, however once I placed it into a distribution box and started switching a fairly large (7.5kW) contactor, the on-board seven segment display started glitching by displaying…
SmileXS4
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When is a programmable logical controller the best choice?

I am studying PLCs as a part of my Elements of Industrial Automation class. Trouble is, I can't imagine why would anyone use such a thing. For complex tasks, microcontrollers are available. The vast majority of practicing programmers are well-versed…
Vorac
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Servo controller

I am working with an LS IS brand servo driver and servo motor. I have some difficulties with getting it to work. Full manual I have to mention that I don't have knowledge in servo motors. I am using a Cypress PSOC (instead of an PLC) to generate…
iconradez
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SSI to RS485 communication protocol

How do I interface a positioning sensor with SSI interface with an OMRON safety PLC with only RS485 interface? I understand both are serial, but would I loose resolution if I interface it?
Kulgaurav Kanade
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Technical term for this kind of PLC I/O?

I don't claim to be an electrical engineer or even an electrician as I work with software more often than hardware, my job does however often work with panel wiring and wiring I/O; I was hoping someone could define a type of wiring for some…
Antony Pain
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Isolating an analogue input using ADC/DAC

I'm looking into isolating an analogue input coming from field equipment and interfacing to a PLC analogue input module. The input will be of the 4-20mA range (1-5V). There are a few ways to approach this but I am currently pursuing the solution as…
JoshGreen1
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Voltage detection / Universal uC Input => CLD, PTC

I'm currently developing a open-source "Home-PLC" for home automation. Every thing runs fine so far and I have a module with fixed voltage AC inputs and outputs. In the next step I want the build 'universal inputs' (power detection @ AC/DC…
Joerg
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How to find electrical conductivity from frequency in my PLC project

I am using a 555 timer which is supposed to measure the electrical conductivity of milk. Here's a circuit for a conductivity sensor: It provides the needed isolation, uses AC measurement, and the output is a frequency which I have wired into my PLC…
Debbie
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Algorithm for converting a 128-bit value to a string

I am trying to convert 128-bit data to a string in a PLC, but the PLC has max. 32-bit data. I store 128-bit data as a byte array and bit array. Now I need to convert this value to a string, but the PLC does not have such a variable. I did some…
Burak T.
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Extending signal duration

I have DMM which is producing pulse with duration of around few microseconds. The pulse need to be sampled in PLC, which has sampling rate of 1ms. In other words the cycle loop can't be reduced to microsecond resolution. So it's impossible to…
Pablo
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