Programmable Logic Controllers (PLC) Information PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options. I/O Channel Specifications Programmable logic controllers I/O channel...
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Q & A on Programmable Logic Controllers (PLC)

We asked our users for their input on Programmable Logic Controllers (PLC). Here are the results of 227 users familiar with Programmable Logic Controllers (PLC).

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing programmable logic controller design?
33 answers
Answers:
In my day to day, the networking technologies are most important to PLC design. Being able to easily pass information and control to a computer both locally and globally is at the forefront of my design work.
~Ken S, Controls Engineer, Cumming, GA
Development of Automotive industries with new technology and fast growing generation wants everything automatic.
~Rohini Kp, Technical Support, Mumbai, India
Open source technology where you can mix & match hardware and software from different suppliers.
~Engineering, Process/Production, Dammam, Saudi Arabia
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Q:
From your perspective, which companies are creating the most innovative programmable logic controllers?
44 answers
Answers:
I like ABB for their ease of use. Setting up a plc or drive is simple and their integration of ideas that make life easier in engineering and the field are cutting edge; (i.e. the ethernet cable extension for the drive controller so programming can be done through the keypad without crouching into the drive space).
~Ken S, Controls Engineer, Cumming, GA
Tridium, Deos, Alerton, TREND CONTROLS, TAC,... all these companies have advantages, and also disadvantages
~Engineering, Process/Production, Las Rozas de Madrid, Spain
By price for Pneumatic Automation "Click - Automation Direct" by Koyo
~Nestor C, Marketing/Sales, Mexico City, Mexico
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Applications and UseTop

Q:
What are some of the applications you have used programmable logic controllers for?
56 answers
Answers:
Standard controlled Packaging equipment for the food industry Servo controlled packaging equipment for the food industry Process equipment for processing food products Control for conveying food products from raw materials thru finished product in cases.
~Greg D, Sneior Control Systems Engineer, Cedar Rapids, IA
I used PLC for many auto-machine : IQF , Refrizer of refrigeration line, packing machine, NC press-break machine ...
~Engineering, Process/Production, HCMC, Viet Nam
Bottle filling stations, concrete production systems, factory control systems and numerous other small systems/units.
~Tim V, Design Engineer, Klerksdorp, South Africa
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Q:
Please share with us any “non-standard” applications that programmable logic controllers have been used for.
16 answers
Answers:
Hmmm, I'm not entirely sure what "non-standard" would include as I believe anything that can be controlled should use a PLC in some form. That's probably not realistic, but it has the advantage of assuring job security.
~Ken S, Controls Engineer, Cumming, GA
Dissolved oxygen control in bioreactors at waste water treatment. Control of rope conveyors for feeding cans into beer can filler. Displaying OEE of packaging lines over head displays.
~Vernon Blanchard, Engineer, Johannesburg, Republic of South Africa
In previous LG PLC I found the step S controller. In Zelio one can toggle on/off with one input.
~Santosa V, Research & Development, Pontianak, Indonesia
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of programmable logic controllers?
12 answers
Answers:
Beware of leakage current through solid state outputs. If you are driving relays you might find that they do not turn off properly.
~Vernon Blanchard, Engineer, Johannesburg, Republic of South Africa
Don't place safety circuitry inside PLC logic unless the PLC is redundant and certified for use on safety logic.
~Greg D, Sneior Control Systems Engineer, Cedar Rapids, IA
Yes by giving wrong Power supply connections to PLC CPU the CPU unit has been damaged.
~Rohini Kp, Technical Support, Mumbai, India
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
28 answers
Answers:
One step visual integration. Although ABB (and Siemens) have a fairly simple interface (I actually prefer Siemens use of Java Applets to ABB's Codesys Visualization) I would like to be able to quickly and efficiently use pre-programmed applets and objects to create the visuals for the programs.
~Ken S, Controls Engineer, Cumming, GA
Programmable in Java, Javascript etc. Dynamic memory allocation. Support simulink code i.e. code generation. Open protocols like JSON etc.
~Mattias Wallinius, Engineering Consultant, Lund, Sweden
Simpler I/O connectivity. Most I/O nowadays use some sort of cable and sub base and the sub bases take up a lot of panel space.
~Vernon Blanchard, Engineer, Johannesburg, Republic of South Africa
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of programmable logic controllers?
18 answers
Answers:
Don't spend money you don't have to. Sure, the new ABB 590 series is great and will do things that some tablet PCs won't, but if you're just controlling a can-opener, you don't need the extras. Engineer effectively, but keep cost in mind ... we have a soft spot for the cool stuff and it can be difficult to say no to the latest and greatest electronics.
~Ken S, Controls Engineer, Cumming, GA
Make sure about sourcing and sinking cards, especially when upgrading from let say a MEDOC to a AB PLC, it is very important! And make sure you understand each card before purchasing (just the basic uses), it saves money
~Louis D, Progress specialist Engineer, Vereeniging, South Africa
Don't be dazzled with specifications from non-established manufacturers or by cheaper equipment from manufacturers who don't have extensive worldwide support and infrastructure.
~Greg D, Sneior Control Systems Engineer, Cedar Rapids, IA
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using programmable logic controllers?
20 answers
Answers:
Sure, use Siemens if you want fast, easy web integration; use ABB if you want integrated software that you don't have to spend extra for the extras and try Omron's line if you want something inexpensive to do minor controls work.
~Ken S, Controls Engineer, Cumming, GA
Ya of course every one should use PLC for all controls because now a days PLC are coming with low cost with a very high speed rate.
~Rohini Kp, Technical Support, Mumbai, India
Buy from established reputable manufacturers that will be around to support your product for its projected lifetime.
~Greg D, Sneior Control Systems Engineer, Cedar Rapids, IA
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