Why S7 PLC so popular? What's the problem with other brands which lead them to be behind S7??

I this an ad for Siemens? It would be a matter of opinion as to what is best.
Is best the one who sells the most? The one with the best communications features? The best acceptance by programmers? The most reliable? Lowest cost for programming the process? Fastest? The most acceptable to European owners?
What is the measuring criterion?

Not all know the typical AWL used in Siemens PLC but when you use KOP or FUP, all brands are quite similar. It depends on what your used to. If a compagny has already alot of a certain brand or they decide to use only 1 brand for the ease of programming, it's normal they use the same or just 1 brand. In most cases that brand is Siemens.

Way back in the late 90s, they were on a mission in the US to rip the market from Allen Bradley. As a result, the price point to get Siemens PLC gear was very reasonable in comparison even to the costs of Modicon. Well, a lot of places bought into the hype, now they are stuck with them. Most customers I know are very dis-pleased with their S7 equipment. I am working on a project to replace a bunch of that S7 gear as we speak. Why you may ask? Here is what I saw here in the US....

1, Siemens went to a bunch of system integrators, and convinced them to switch to S7
2. These integrators gave Siemens a list of their customers(This is the short version!).
3. Siemens bypass the integrators, and told the customers that they would do the engineering for free if they bought from Siemens directly. This cause the systems integrators involved to loose their customers.
4. After a few years, most of the people that could program S7 were Siemens people.
5. Siemens left their customers high and dry with performance issues, lack of support, and bad supply issues.
6. Now, companies are scrambling to not only find people who can reverse engineer the S7 systems, but replace them.

Bonus. If you do not have the original program, you are screwed!

The whole Siemens PLC thing has been a night mare for many clients. It is too bad. It is nice gear if you can get it, and find some support for it.

1. S5 captured big market, before today's players had company itself.
2. S7 is getting its marketshare by migration.
3. reliability
4. No of people who have siemens experience
5. brand name
6. major number of OEM from europe and esp germany....


all above in reasons in exact position for being reason.. plz defend...

i guess we have no reason to speak here what Siemens did... Siemens is ruling thats the fact!!

As an integrator who has worked with both Siemens S7, Allen Bradley, and various other PLC platforms I can say that there are several things that do end up being a matter of opinion, but from my experience I would prefer S7. There are multiple reasons that many integrators prefer S7, but the biggest item to note is the way function blocks and data blocks function as opposed to AB.
In Siemens you have the ability to write function blocks that will have instance data blocks which track variables and allow you a very clean interface to a chunk of code. Additionally you can configure data blocks to have various different data types organized in any way you choose (as opposed to AB where you have a block of integers, a block of timers, ect).

That being said it is hard to say that one PLC platform is better, as there are different advantages to many different platforms, however, the modularity of S7 tends to make it easier to use and understand.

If you want any further elaboration, I would be happy to discuss it, and actually in the next few days one of my coworkers will be posting a blog with a in-depth objective analysis of AB vs Siemens that I will post here.

Our company provides automation and integration for both Siemens and AB along with other brands.
Certain industries utilizes certain brands etc... Siemens has some amazing feature to it, where AB has now integrated alot of the same mentality utilizing UDT, ADDON instruction etc. The difference between the two are getting smaller and smaller.
Siemens tends to lean more towards the higher level of coding (STL, SCL) while still providing basic ladder logic and AB started with more simplistic ladder logic and now graduating to higher levels as well.
But regading ladder logic style of code, AB beats Siemens hands down. Especially when it comes to online editing, troubleshooting etc...
In short....my views...
Both platform can be designed to perform amazingly or poorly...It is all based on the engineering principals used in the design and development of the project/package.

Having used both as a person who has to maintain and repair the system and all associated equipment I much prefer AB and ladder logic to Siemens and the higher level programming functions. Of coures part of this bias is having learned ladder logic first. However working on continuous process I find that making online changes to the system is more fraught with danger on the more sophisticated systems. I have been blown out of the water more and have had to halt the processor many more times with function blocks etc than ladder logic.
from my point of view the advantages of the newer systems are accrued on teh contract programmer side of things more than the operations side.
The selling point was that more is spent on programming than any other and this would save money overall. That may be correct, but I find the the few programmers that are truly familiar with the system in my industry can cahrge more and most of our programmer analyst in our company in this country are from Europe and have difficulty in communicating with our production personnel.
While I can keep the systems running I would be more comfortble with AB or Modicon. Perhaps this is my age and lack of extensive training with Siemens showing

Interesting discussion. Having worked for Siemens (S5 and S7) and Mitsubishi and also worked on a lot of AB PLCs (SLC500, PLC5.
Really, in terms of looking of pure processing horse power, Mitsubishi Q series have both Siemens and AB beat hands down. Don't about function block comparison as it has been a while that I've done massive amount of PLC coding with Function Blocks, and Data Blocks. I don't work for any of them so have no interest in supporting any particular vendor. Mitsubishi Electric Automation Q series has the smallest foot print, and high density I/O modules, smaller than SLC500 series and S7-300 modular. AB ladder is the worst in terms of having higher level functionality, not sure who wins between Siemens and Mitsu.

Just my 2 cents!
Cheers

@Tsien I like the Mitsubishi/CClink platform also!

I found the comment on density and footprint interesting. There are two points of view here. The panel shops and OEM realy like high density an packing more I/O into less space. From my point of view as one who maintains and modifies production systems I like lower density where wires can be more easily tracedwith less chance of knocking that loose wire off its terminal.
Recently I was involved with a Siemens PCS7 install for a lime kiln that used the high density compact I/O and it is impossible to even get to a terminal to verify signal at the input or output. Also the high density caused high temp problems and intermittent problems. I really hate to have to resort to fans to keep I/O cabinets cool enough to operate reliably.
I guess this is a problem whenever an engineering company and panel builder fails to consider power and heat dissipation whatever the format.
The larger presumably more rugged lower density I/O would let the technician get to the terminals and trace wiring and also keep the watt density down.

Just my $0.02

Best regards