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Questions tagged [plc]

PLC (Programmable logic controller) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures.

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Learning PLC programming

How do I learn PLC programming? Would it differ greatly for different brands of PLCs? Is ladder programming the same as PLC programming?
Aydya
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PLC Version Control

I need to come up with a CM process for PLC code. Currently, the system is developed using RSLogix 5000. The build product is a monolithic file that can be loaded onto a PLC for execution and edited directly in the development environment. With…
Dave
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Is there a good library for dealing with the Modbus protocol in .NET?

Does anyone know of a good (preferably open source) library for dealing with the Modbus protocol? I have seen a few libraries, but I am looking for some people's personal experiences, not just the top ten Google hits. I figure there has to be at…
GEOCHET
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Alternative to OPC-UA

Is there any decent alternative to OPC-UA as a solution for accessing process data of a system composed of various PLCs? Something that is platform independent and can "speak" with products of different brands ? I've heard of MQTT but it seems to be…
cid
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Connecting an PLC Siemens S7-1500 to an SQL Server Database

The connection guide is here. I track the guide and do a lot of stuff. The connection between PLC and SQL server is ok, I've login successfully to SQL. I can insert to tables, update, and execute store procedures. But when I run a select query I…
Peyman Majidi
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How to Convert pythons Decimal() type into an INT and exponent

I would like to use the Decimal() data type in python and convert it to an integer and exponent so I can send that data to a microcontroller/plc with full precision and decimal control. https://docs.python.org/2/library/decimal.html I have got it to…
ericnutsch
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6 answers

Being a better / more efficient PLC Programmer

The company I am doing my intership/appretinceship in, does mainly PLC programming with Siemens modules. Comes from the fact that most of the people were electric guys and switched over to engineering. My problem as newbie there is, that I can't be…
Faizan S.
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2 answers

What is a Historian?

What is the function of a historian in terms of OPC and PLC?
Rob_IGS
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11
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5 answers

Testing ladder logic

We all know the various ways of testing OO systems. However, it looks like I'll be going to do a project where I'll be dealing with PLC ladder logic (don't ask :/), and I was wondering if there's a good way of testing the validity of the system. The…
Erik van Brakel
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Good open source OPC software

We are currently using a free trail version of KEP Server for our OPC to communicate with our PLC. We were wondering if anyone knows of any good open source OPC software.
Rob_IGS
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1 answer

Access Siemens S7-1200 through C# Application

I'm trying to access the Siemens S7-1200 database to set and read tags through a C# executable that I will run on Windows. The intention is to have a desktop app that can establish a connection with a PLC over Wi-Fi / Ethernet. The app will then…
itstudes
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How can I communicate between a Siemens S7-1200 and python?

I am running a process on a S7-1200 plc and I need it to send a start signal to my python script, after the script is done running it needs to send something back to the plc to initiate the next phase. Oh, and it has to be done in ladder. Is there a…
Megimoo
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C# OPC Applications Identical Code, but work differently

I am developing a C# custom OPC Client, I started off writing in a console app for quickness, everything works perfectly as I want it to. Then I decided to make a windows form application for a visual experience. The windows form application just…
SK2017
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A clever homebrew modulus implementation

I'm programming a PLC with some legacy software (RSLogix 500, don't ask) and it does not natively support a modulus operation, but I need one. I do not have access to: modulus, integer division, local variables, a truncate operation (though I can…
Ben Mordecai
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Send FINS command from C# to PLC

I try to send FINS commands through UDP from PC (C#.NET) to PLC Ethernet module (Omron), but is not getting any responds from the PLC and have no clue where I can start troubleshooting. PLC has a very simple ladder logic as follow: If DM100 has…
KMC
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