I am looking for a comparison of PLC systems between different PLC manfacturers. Typically in the Small to medium size range. I am particularily interested in comparing, Allen Bradley, Modicon, Siemens, Omron and Automation Direct. I would like to have a comparison of I/O capabilty (Local and Remote), Memory sizes, networks supported. CPU Features etc.

Any suggestions or Web pages as to where I can get this sort of information.

 

If you contact the Schneider sales office nearest from you they should be able to give you a comparison between Schneider PLC's and other ones from the market.
I do not know any web site that has this kind of information.

 

Automation Direct has thumbnail comparisons, but clearly they have a slightly biased comparison.

 

> > Any suggestions or Web pages as to where I can get this sort of
> > information.
>
> Automation Direct has thumbnail comparisons, but clearly they have a
> slightly biased comparison.

Quite frankly this type of comparison is of little value in the real world. People choose their PLCs for different reasons, but arbitrary lists of features is generally not one of them.

If you want to pick the "best" PLC family for you application, I'd suggest creating a list of the following:

1. Things that are absolutely required
2. Things that are strongly desired
3. Things that are nice, cool, nifty, etc, but not really all that important

I think you will find that all PLC families will generally fulfill 1 and 2 above (unless you artificially select features as required when they really aren't). Most of the differences will be with the "things that are nice" category.

Bob Peterson

 

When I had to chose a brand of PLC I tackled it this way. I did not need nay special features so I chose 6 brands that included what i needed.

Then to find out who offered the best price I did the following. I drew up three differnt sized systems.

10 off Small Stand alone PLC no network, no HMI max 80 I0
5 Contactors
10 relays
10 illuminated pushbuttons
5 switches

3 off Small netwoked 250 I/O HMI option
1 Varispeed drive
20 illuminated pushbuttons
10 switches

1 large system 500 i/O
3 Varispeed drives
20 Contactors 4kw
20 Relays
50 Pushbuttons illuminates
20 switches

Each supplier priced each basket.

The range in price was astounding. I had chosen to stay with one brand for all components to simplify maintenance & stock holding.

I could have made a small saving by chosing the cheapest component in each brand, but I am glad I did not.

I wont who say who came out cheapest but I whent with them and did not regret it.

Stephen

 

I thought that Bob's advice was pretty good. Write down your "wish list" and search on those items.

If you have difficulty finding some of these key items on the PLC vendors websites, throw those in the forum and I think you will find answers. I would try to avoid "analogous" questions that will invite opinions. I would try and ask "binary" yes or no questions.

I think that you will find that opinions on PLC vendors are much like opinions on car manufacturers. One person will swear that Ford is better than Chevy until his dying breadth and another person will swear the opposite.
If you are planning on doing many different applications of various sorts, it would be my opinion that you consider not only one PLC vendor but maybe a few. You will find in your research and in talking to some people that have been doing this a while that no one PLC vendor is perfect for every application. It usually comes down to a price vs. performance judgement call. There are definitely PLCs out there that are cheaper than others and there are definitely PLCs that will out perform the others. I've never seen a PLC that was superior in both of these categories in every situation.

 

I tend to focus on which supplier/product range will have a good chance of being easily supported in 10 to 15 years from now. Is their history one of introducing good products that stay the market for long times e.g > 8 years Do they have common PLC programming across the range small to large..

Cost of hardware can be ignored since the life cycle cost is mainly software and software support.

You could say who is the "Microsoft" in the PLC market.

 

You aren't taking Mechatronics with Dr. Hamel are you??????

 

Would you be willing to share the results of this survey including prices?

please send to [email protected]

 

I am sure it was a fun exercise seeing which manufacturer was the cheapest. You went with them and you were happy. Wonderful. However, for example, your discount factor would not be the same with all suppliers. Also, you could have been happier with a slightly more expensive (or even the most expensive) supplier &c &c. You would never know this unless you had some sort of scientific approach.

I still find the "who has the best SCADA", "who has the best PLC" and so on questions less-than-useful.

Perhaps someone could craft a real scientific survey? I doubt it.

RA

 

I sold Allen-Bradley and Télémécanique PLC in the past. Now I'm using Siemens and Automation Direct PLC at work.

MY OPINION is that Allen-Bradley is one of the best company for technical support and ease of use of their product. But they are not cheap $$$. Siemens do great PLCs but the learning curve is hard and the price is also high.

Automation Direct PLC is very cheap and takes less space for the number of I/O you need. Less space means small IO cards with very small screws to retains your cables. It is very easy to break those screws and connectors on card ar snaped.

Hope it can help.