diffrence force between s7-300 & 400

unclehamid

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Feb 2007
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I 'd like to know if force is different in s7-300 and 400

because I saw an article that said they are diiffrent but didn't explain about it
 
From Step 7 Online Help...

Force2.JPG


Nick
 
The 400 is an older platform, has a larger footprint, is generally more expensive, and has more quirks in communications. I don't think new products are being developed for it as much as the 300.

The 300 is the platform I would recommend for new applications, and some of the 300 CPUs have more memory and better speed than the 400's.
 
Sorry Tom, but it's astounding how such misinformation from a normally reliable source can unintentionally become the 'official' opinion on some equipment. I just feel I have to comment.

The S7-300 and S7-400 are not significantly different in age. I've no idea whether the first S7 CPU to be shipped was an S7-400 or and S7-300 but I'd bet it was only a matter of weeks or days between them. We are not looking at different generations of PLC.

The S7-400 is a larger format than the S7-300. I heard this was a deliberate design requirement as Siemens wanted to provide some form of compatibility with their several thousand S5 installations world-wide. Although I've never used one, you can get an S7-400 carrier module which allows old S5 I/O cards to be inserted in to an S7-400 rack and treated as part of the native S7 I/O. I guess this is similar to the inclusion of S5 timers in S7 (300 and 400) software.

For a given task, an S7-400 probably will be more expensive than an S7-300. But there are some tasks I just would not use an S7-300 for. What about hot-standby, what about fail-safe operation, what about ...

I'm not at all sure about the "quirks in communications". Can you give some examples?

There's no doubt there is more activity and change in the mid-range PLC market overall so it's only natural that the S7-300 will appear to to be the system being developed more frequently. New CPUs seem to be dropping out of the sky all the time. In terms of I/O, since Siemens have nailed their colours firmly to the Profibus mast any developments in this area will benefit S7-300 and S7-400 equally.

"...some of the 300 CPUs have more memory and better speed than the 400's". Yeah, and some of them don't. There's an overlap in the ranges. What manufacturer doesn't have this? And some S7-400s have memory way beyond the stretch of S7-300s. As far as I'm aware Siemens DCS offering, PCS7, is based entirely on S7-400 processor hardware with Profibus I/O. Although it's not programmed as a PLC it seems clear that Siemens themselves are are putting their vote behind the S7-400 architecture for that market.

I'm not supporting either the S7-300 or the S7-400: I'm just trying to balance what seemed to me to be a rather skewed vision on these products.

Regards

Ken
 
About differences between S7-300 and S7-400:
I think that S7-300 allows max 10 forces. This is less than the S7-400, but I dont know exactly how many the S7-400 allows.

About the S7-400 not being developed:
It is true that Siemens fastest offering at the moment is the S7-319. But there is a lot of development going on on the S7-400. They just released the "5" generation with many enhancements. And yes, as PCS7 seems to require the S7-400, this platform is not going to go away in the forseeable future.

A completely different discussion is that the growth in the PLC market is in the small or compact PLC range.
 
Nearly all of my projects during the last 10 years have been with the S7-400, mostly because they blew the closest 300 series away in peformance. I can't recall any communications problems.

I think most of these rumours start with misinformed Siemens reps. Some of them are great, but I still hear misinformation from them that blows my mind.
 
It's more about the backplane:
400
Parallel Bus (Big Bandwidth)
Multiple CPU's on one Rack (4 Max)
Ability to share resources (Ethernet Cards etc)
Red. CPU's
Profibus Modules Cards map directly into I/Q area (not through read/write)
Hardware Updates (Cir) in run mode
DCS (PCS7 Platform)
4 Accumulator Stack

300
Serial Backplane
Single CPU
No Red. CPU (Hardware based system)
"Slot-less" Rack
2 Accumulator Stack

400 = Large Resource, Large Performance CPU
300 = More Nimble single CPU design

Nick
 
OK - guilty of assumptions. (Some)

I am relying on info for others as far as the questions of age and future development goes. However, as you and others have mentioned, most of the activity is in the 300 series.

And, as others have verified, the 300 has some (but of course not all) faster and more powerful processors.

Very few applications need redundant CPUs, hot standby, etc. If you do, then obviuosly you use a platform that has it. If you don't why spend extra money and consume more panel space?

The communications quirk I had was on a mixed 300/400 system. When the comm cable was pulled all memory in the block was zeroed out instead of holding last values the way other manufacturers I've used do. This may not be exclusive to the 400, but I hadn't experienced it on 300 only systems.

I'm a little surprised by the antagonistic tone, Ken. I don't think I was bashing either platform. On the other hand, if I'd expressed my full opinion of Siemens you'd have cause to be offended.
 
I'm a little surprised by the antagonistic tone, Ken.
My apologies Tom. I really tried to preface my opinions with lots of compatible words and phrases like "Sorry ...", "...a normally reliable source...", "...unintentionally..."

Whether you were bashing or not wasn't uppermost in my mind at the time. However having re-read your post, you "recommended" the S7-300 without reservation, and listed nothing positive at all about the S7-400. Hmmm .... yes... on reflection I'd call that bashing :)

I genuinely didn't think I'd challenged or opposed any of your opinions. You have yours and I have mine and we're both entitled to them. What I did try to do was offer additional facts.

Finally I suppose I should be delighted you said you were "surprised" by my antagonistic tone. At least that means you weren't thinking "Oh here he goes, stirring things up as usual"! ;)

Friends again?

regards

Ken
 
Ken M said:
Friends again?

Not AGAIN, rather "friends still".

I wasn't really offended, just surprised in that I thought I had inadvertantly offended you and I didn't plan to denigrate either product.
 

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