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Redundant Control Systems: Siemens S7 400H Series PLC and WinCC
Cesar Pena

Redundant Control Systems: Siemens S7 400H Series PLC and WinCC

There are certain control systems, such as in nuclear power plants and airplanes, that cannot be disabled or shut down, even momentarily, because of the threat to people’s lives. In these applications, a redundant control system must be in place to take over instantaneously if the primary system fails. I recently deployed one such redundant control system for train tunnel ventilation at a major international airport. The system's main objective is to control, reduce, and help exting...

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IEC61131-3 Data Structures (Encapsulation = Domination!)
Tim Jager

IEC61131-3 Data Structures (Encapsulation = Domination!)

Encapsulating your data into custom Data Structures will allow you to Dominate (maybe not the world, but at least your PLC) I'm going to conclude my series on the IEC 61131-3 standard by examining the benefits of Data Structures. (If you missed my other posts, you can check out the previous part 1, part 2, part 3) Before we dive into Data Structures, let's review basic data types. Every PLC supports a certain group of standard data types. The list typically includes the followin...

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Communication between Siemens HMIs and non-Siemens controllers
Jon Carson

Communication between Siemens HMIs and non-Siemens controllers

Ever wanted to use those very nice looking Siemens touchpad HMIs with a third party controller Siemens doesn't officially support? On a recent project I was presented with the following scenario: a customer already had several Siemens touch-screen HMIs in stock, and wanted to use one to help operators control an Elau motion controller. Of course to do this I had to get the HMI and controller to talk to one another. The HMI understood about 20 different protocols — everything from Allen...

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IEC 61131-3 Function Blocks - Unleash the Power!
Tim Jager

IEC 61131-3 Function Blocks - Unleash the Power!

If you are a programmer, an OEM, or end user that utilizes IEC 61131-3 compliant PLCs, you should MUST read this article. In the 3rd part of my series on the IEC61131-3 programming standard (you can check out the previous part 1 and part 2), I will explain the huge benefits of structured programming and why Function Blocks are the greatest thing ever....seriously they are awesome and worth using in every PLC program. So what is a Function Block anyway? A Function Block is an encapsulate...

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IEC 61131-3  Choosing a Programming Language
Tim Jager

IEC 61131-3 Choosing a Programming Language

This is part two of my series on the IEC-61131-3 programming standard. Here's a link to Part 1 for those of you that missed it. The IEC61131-3 standard contains 5 different programming languages. This article will give a brief introduction to each one and some tips on choosing which language is best. The five languages: Ladder Diagram is most popular in the USA. It is based on the graphical presentation of Relay Ladder Logic. Most non-IEC61131-3 compliant PLCs only support ladder lo...

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Nick Shea

Safety PLC Impact On Software vs. Hardware Debate

After working on several projects with Siemens S7-300 Safety PLCs, I was given the opportunity to contribute to an article for ControlDesign.com that presents cases for and against replacing hardware components with software solutions in machine control. From my experience, I have seen some direct advantages of replacing hardware such as a safety relay with a safety program in a safety-rated PLC. Some benefits of going this direction are: Wiring Advantage Single pair of contacts a...

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Remote IO Configuration for Simatic 505 - As Easy As 3-4-5...
Nick Shea

Remote IO Configuration for Simatic 505 - As Easy As 3-4-5...

While commissioning the automation controls for a manufacturing line, I acquired some tips and tricks for configuring a Profibus network on a Simatac 505 (formerly known as a TI 505). Using 505 Workshop version 4.32 development environment from Fastrak Softworks, I was able to utilize their built-in Profibus I/O configuration tool instead of the out-dated COM Profibus application. Whereas I've commissioned several systems using a Siemens S7 PLC with remote IO and VFD connections via Profi...

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Vijeo Designer Version Control with Tortoise SVN
Danny Budzinski

Vijeo Designer Version Control with Tortoise SVN

I was working with Vijeo Designer 5.0 on a recent project and, overall, found it rather enjoyable to work with. Vijeo Designer is the Schneider Electric / Telemecanique programming software for the Magelis XBT-GT HMI's along with several other SCADA platforms. The creation of variables let me organize my I/O into logical folders, the alarm setup was intuitive and let me create specific groups en mass, and the page designer let me create an object with pretty much any look and feel that I ...

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Siemens Simatic S7-300 - Retaining Values When Downloading a Datablock
Kristie Simon Shea

Siemens Simatic S7-300 - Retaining Values When Downloading a Datablock

A simple yet common problem when programming a Siemens Simatic S7-300 PLC is losing the data already stored in the PLC after downloading an updated data block. If you are simply adding items to the end of a flat data block (not adding items to a user-defined type (udt) within the data block, for example) then to retain the values of the data block follow these quick steps. Go online with all of the blocks in Simatic Manager. Copy the online version of the data block whose values you w...

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Siemens S7 PLC Troubleshooting
Jon Carson

Siemens S7 PLC Troubleshooting

Once you are familiar with their capabilities and methodologies, Siemens PLCs have the potential to make controls programming quicker and easier than ever. With support for function blocks, text-based programming, libraries, and user defined types, Siemens lets developers attack problems with a much more object-oriented approach than traditional ladder logic programming. But for programmers and technicians less experienced with the Siemens line of PLCs, The S7 and S5 product lines often seem ove...

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Working with Legacy Hardware: Tips and Tricks
Danny Budzinski

Working with Legacy Hardware: Tips and Tricks

For a DMC engineer it is not atypical to be faced with outdated, legacy technology. Maybe a customer has come to us to upgrade a system that an intern did in the 90's; maybe a company's engineers have built up a system over the past decade and need help configuring or adding more pieces to it; or maybe a factory has used a controller that was made when you were in middle school and all of a sudden that controller breaks down and needs to be replicated and replaced. Regardless of the situ...

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Empowering your PLC with IEC 61131-3
Tim Jager

Empowering your PLC with IEC 61131-3

Nobody loves catchy numeric buzzwords as much as me. I - E - C - Six - Eleven - Thirty - One - Dash - Three.... It just rolls off the tongue! OK I admit, it's a mouthful, but trust me it's worth knowing about. This is a brief intro to IEC61131-3 and the first part in a series of posts that will cover its features and benefits. So what is it? The International Electro Technical Commission (IEC) is a non-profit organization that develops standards for electrical and electronic techno...

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DMC at NIWeek 2009
Darren Jones

DMC at NIWeek 2009

Every summer, National Instruments holds the NIWeek conference in their home town of Austin TX. This year, DMC has three of us attending: Jesse Batsche, Eric Nielsen, and myself. Monday was “Alliance Day”, tailored to NI Alliance Members, as well as the day for various closed sessions, such as the Big Physics conference to address technologies and trends related to large scale physics applications (particle accelerators, extremely large telescopes). Tuesday through Thursday is ...

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Arrival at NI WEEK 2009
Eric Nielsen

Arrival at NI WEEK 2009

Darren, Jesse, and myself (Eric N.) arrived in Austin TX yesterday to participate in National Instruments' yearly technology symposium and trade show NI Week 09. The activity started early today with a great keynote presentation. Most notably was Alex Davern's (National Instruments CFO) "lesson" on economics and NI's approach to weathering the economic downturn. "Competitors are throwing the baby out with the bath water and we want to be there to catch the baby." ...

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Remote Machine Monitoring–Connecting to a Modbus Network with Java and Jamod
Jon Carson

Remote Machine Monitoring–Connecting to a Modbus Network with Java and Jamod

For a recent project, I had an interesting challenge. It involved a (relatively) simple control system, with an Allen Bradley MicroLogix PLC, and 30 or so inputs and outputs. The challenge was that the customer wanted to be able to access (and potentially control) live machine data from anywhere on their network, while buying as little hardware or software as possible. After a bit of research I came up with the following solution: The only entryway to the data that was available with no a...

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State Transition to Ladder Diagram Translation
Eric Anderson

State Transition to Ladder Diagram Translation

Ladder diagrams are an industrial programming language typically used on programmable logic controllers (PLC). This graphical language mimics a relay logic electrical schematic. For engineers that are not familiar with relay logic, though, ladder diagrams can be difficult to implement, debug, and maintain, especially when programming complicated machines with many inputs, outputs, and states. In these applications, the state transition diagram or sequential function chart are better tools. Bo...

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Kevin Johnson of ILF Visits DMC for the Week
Kristie Simon Shea

Kevin Johnson of ILF Visits DMC for the Week

During this past week, DMC had the opportunity to work with Kevin Johnson of ILF Technologies at the DMC office. ILF, located in Romeoville, IL, produces web finishing products for the printing and converting industries. The machine we are currently working on is a new Sheeter which runs on Siemens' SIMOTION platform. Kevin is intimately familiar with the functionality of the existing Sheeters and he has solid knowledge of the existing code base. In order to be most efficient and provi...

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Solar Panel Project Featured in Design World
Frank Riordan

Solar Panel Project Featured in Design World

A Solar Panel Assembly Project that DMC recently completed was the basis for a feature article in Design World Magazine. The article can be found here. DMC provided controls engineering and programming services for a company that makes machines that are used in photovoltaic production facilities. The system developed utilized a Siemens 317T Controller which provided both discrete control as well multi-axis coordinated servo motion control. The customer benefits of the solution DMC devel...

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PC-Based Controls vs Dedicated Controllers
David Simmons

PC-Based Controls vs Dedicated Controllers

Mike Bacidore over at ControlDesign.com has written an insightful article discussing the recent shift of many of their readers from using traditional PLCs (Programmable Logic Controllers) to using more powerful PACs (Programmable Automation Controllers). I believe this points to an overall industry trend towards customers wanting robust and reliable systems which are more intelligent, and able to transfer data easily from device to device. Mike also notes how a smaller number of his readers p...

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