Technical Questions

joeyb23

Member
Join Date
May 2004
Posts
14
I know all the business questions to ask a manufacturer about when choosing a plc line-----but what type of technical questions should i be asking???

Thanks Again,
Joe
 
You could be asking things like:

-What power supply is needed for the CPU
-What type of card are used (relay outputs, transistor outputs, are the analoge signals galvanical sepperated from eachother, and so on)
-Is there a battery back up for the programm or data storage or is an eprom used (or other type of storage card/memory)
-What about spare parts, is it a commonly used plc, if you have to order spare parts how long will it take to get them.
-How is the programm set up, what kind of programm structure are they planning to use
 
It also depends on the particular applications you require the PLC for. You can add some considerations like:

- High speed Digital inputs/outputs availiability
- Communication ports and protocols (if your application requires to integrate serial communications with drives, HMI, etc..)
- Networking (as a must!), most of today applications require to network PLCs.
- Programming software and user licenses(price is here a good consideration)
- Technical support

Hope it helps.
 
Someone can come and ask I have application which need PLC with servo control ability work with 2 mode of control also I need 3 com port
and HMI.
Also needed absolute position control.
and of course cheap price it must be very economic system.
Tough question?
In most cases that what you going to be asked.
You also consultant.
I expect to professional answer.
I dont want to upset you I am realistic.You need to prepare your self.
 
When considering communications/networks, ask how easy it is to implement serial communications to other devices. This is most important. Also have a good look at what type of field busses are available. Would suggest, at a minimum, Device Net and either Profibus or ASI. Also have a good look at pere to peer networking. Some PLCs do not handle this efficiently and it can be difficult to implement. The easier the better. I still prefer token ring for networks. Far more efficient, from my experience.

The biggest time saver is software. Have a good look at the software, particularly speed of development and ease of use and tools when online programming and monitoring. If you are likely to require online programming make sure the PLC and software are able to handle this in an unqualified manner. Altering and downloading sections of memory areas, for example, are essntial for large projects. After altering data memory areas for analogue cards etc it is also essnetial that there is a card restart bit available. Just be careful that there is not something crucial, such as frequency, hanging off the card when you restart it.
 
I think this may be the begining of the longest thread.....

In my opinion you can go on forever on this issue. There are four main components involved. Hardware, Software, and Learning curve/support, and YOUR application. Wide open question....
 
Here is another aspect:

If you already have equipment installed, what have you got, are you happy with it and are your maintenance and operations staff happy with it?
Also, with your present system, where in its life cycle is it. Is it new or old? Are the parts still in production? Is it current?

Best is extremely relitive.

Doug
 
Coincidence

I just had a vendor in yesterday. Some of the technical questions that I asked:

Online programming capabilites?

Search and Replace with Wildcards?

Memory limitations? Upgradable? If so, how, and how much?

Distaster recovery. (If PC gets hit by a forktruck, taking my latest, un-backed-up code with it, what are my options?)

Speed (assuming bare-bones program) Include I/O update times. Interested in fastest "round trip" from sensor to input to PLC to logic to output to device. Only for those systems that really need it.

Technical support network: Distributer, manufacturer, user forums; phone (24/7?), email, websites (tech database). Etc.
 
From A manufacturer's standpoint...

All questions are good to ask, however, you should have developed a business plan ahead of time. If you are considering adding a product or capability, you should know what you want to accomplish. Will this product add to our capabilities? Will it increase our potiential customer base? Will it provide us with a competitive advantage over our competition?

When interviewing potential vendors, make certain that the product fits your plan.

The capabilities of manufacturers will differ, as will the capabilities of product. Some may be stronger on one aspect, while weaker on others and vise versa.

The questions you formulate, should be related to the goals and criteria that have been set within your business plan. Specifically, the technical questions should relate to your specific needs and concerns.

With regards to PLCs...whoever you interview with (representative of the company) should know the product inside and out. He should be able to relate their products to the competition and provide you with pros and cons of their products vs. other manufacturers. With the larger companies, chances are you will meet with a manufacturer's rep (independant of the company), or possibly a regional sales manager (employed by the company)...know who you are dealing with, because the level of information you receive will be different. The factory rep, should be able to provide you with more detailed information while the mfg. rep. information will be less detailed. If you are looking for technical information, chances are most sales reps will not have the information you require...they will probably have you deal with a technical support reprensentative.

Eventhough I didn't provide you with specific questions, hopefully this will give you direction as to how to formulate your questions, based on your company's needs and goals.

God Bless,
 
The name says it all

joeyb23 said:
I know all the business questions to ask a manufacturer about when choosing a plc line-----but what type of technical questions should i be asking???

Thanks Again,
Joe

Big questions, I was where you are in 1981.

Most PLC manufactures will/do support most all apllication. (the Big Sweats off)
Costs- I/O Modules/Cards could be a major concern
Post Sales Support both with Hardware and Software This is the most important part of the equipment, do you have a local distributor?
What about that 2 A.M. Saturday Failure who are you going to call and can you get the part now not next week.
 
"What about that 2 A.M. Saturday Failure"

they all have this feature. some come standard with it, and others are optional.
 

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