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Siemens vs Allen-Bradley: Function Blocks
Nick Shea

Siemens vs Allen-Bradley: Function Blocks

Siemens and Rockwell Automation are two giants competing in industrial automation technology today. Rockwell (aka Allen-Bradley) seems to be more popular in the US market, but Siemens has a larger international customer base. A cursory Google search will reveal that there is no lack of debate among automation professionals over which one is preferred. On the higher end of their PLC lines, the programming environments to use are: Siemens - Step 7 Simatic Manager for S7-300 and 400 level ...

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Successful Implementation of Siemens' SiMotion Shaftless Drive Standard
Kristie Simon Shea

Successful Implementation of Siemens' SiMotion Shaftless Drive Standard

In many industries, shaftless drive technology has replaced the old mechanical drive systems. Instead of using mechanical gearing to force one axis on a machine to follow another one, servos are used. The servo technology reduces many of the flaws of a large mechanical gearing system as well as provides a lot of flexibility. This technology is in heavy use in industries such as the automotive, packaging, and printing. Using the shaftless drive technology requires the use of a motion controlle...

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Object Oriented Programming in Siemens and Allen Bradley PLCs
Jon Carson

Object Oriented Programming in Siemens and Allen Bradley PLCs

Since their conception PLC programs have been founded on simple programs. RLL (Relay Ladder Logic) and IL (Instruction List) commands have dominated PLC programs since PLCs first came to market in the 1970s. However in the past few years automation requirements have grown more complex and demanding. This has in turn led to PLC manufacturers beginning to include some higher level programming concepts in their software packages. What exactly have they added? And what does it mean for your manufact...

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PLC Analog IO Troubleshooting Tips
Nick Shea

PLC Analog IO Troubleshooting Tips

When commissioning or troubleshooting PLC inputs and outputs (IO), the analog signals are often the most difficult. First, analog IO almost always has to be scaled to convert the raw signal to useful process values. Also, there are many wiring and external device (sensor/actuator) configurations. Here are some simple guidelines for troubleshooting and working with Analog IO. Although these guidelines are intended to help you think about the process of troubleshooting, this process will surely...

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PLC Troubleshooting
Matt Puskala

PLC Troubleshooting

We are frequently asked to work on PLC systems for clients that we did not develop. The job could be troubleshooting an issue or adding a new feature to the system. Working with unfamiliar code has its own unique challenges, although we take pride in our ability to do so. Here are some things you should keep in mind when asking an integrator or even your own internal maintenance staff to take a look at your PLC system. Source Code Almost every PLC system I've worked with does not store...

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"Indirect Addressing" in Step 7 Basic v10.5 SP2
Nick Shea

"Indirect Addressing" in Step 7 Basic v10.5 SP2

For those of us who appreciate and harness the power of indirect addressing in Siemens S7 300 and 400 level PLCs, we were sad to hear that this functionality was not supported in the same way for the new Step 7 Basic software for S7-1200 PLCs. As of Service Pack 2 for Step 7 Basic 10.5, however, Siemens has added array indexing functions that get you closer to indirect addressing. They are called "FieldRead" and "FieldWrite". Essentially, they are functions that allow you ...

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Siemens S7-1200 PLC communicates through Sinaut MD720-3 cellular modem
Nick Shea

Siemens S7-1200 PLC communicates through Sinaut MD720-3 cellular modem

Many consumers, including myself, have tapped into the ever-growing functionality of mobile internet. Many people leverage this infrastructure for their mobile phone. Others are beginning to use WiMAX connections for their PCs. Not to be out-done, PLCs are also capable of communicating through wireless data plans. DMC just finished the proof-of-concept phase in a project using the new Siemens Simatic S7-1200 PLC and Siemens Sinaut MD720 GPRS GSM cellular modem. We were able to successfully se...

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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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