S7-200 and S7-300 PLCs...questions

Hi everyone,

I am looking for a Siemens PLC for a high speed application(not a HSC) requiring precision in milliseconds or even better. It uses 6 inputs and 5 outputs. For a similar application, I have used the S7-200s (CPU 222 and then CPU 224XP). The scan time came to 3-5ms. My questions:

• I know it depends on the program but if I use a S7-300, will I see a significant difference in scan time? Say, get 1-2ms?
• S7-200s costs around $495, how much would be the approx cost of S7-300?
• What is the difference between the S7-300 and 400 series? Is it just the processing speed?
• I know the programming software is totally different, how is the compatability between MicroWin and Simatic Manager?

Thanks!

I know it depends on the program but if I use a S7-300, will I see a significant difference in scan time? Say, get 1-2ms?
No. Even with no code running at all (just a BEU in OB1), the scan time will be close to 1ms. Except for the new 318, the 300 series really aren't known for speed.

S7-200s costs around $495, how much would be the approx cost of S7-300?
You need to call your supplier. But the 300 will definitely be more.

What is the difference between the S7-300 and 400 series? Is it just the processing speed?
The 400 is much faster, but also supports much more hardware and advanced configurations. It's the difference between a VW and BMW (and they cost much, much more).

I know the programming software is totally different, how is the compatability between MicroWin and Simatic Manager?
As far as I know, there is no compatibility. The 200 is sort of related to the old TI, but the 300 and 400 were developed entirely by Siemens and are closely related to the S5. I wouldn't count on porting much knowledge over from the 200 series.

If you really need precision, and would like to get reponses under 1ms, take a look at the 300 series Cam Contollers and other special montion control cards. They will definitely do the job. And, they are easy to configure. Just ask RMA.

Thanks for your reply... Yes I am looking for a less expensive alternative to the S7-200s for better processor spped. I will check the Cam controllers..

What processing does your application perform between the inputs and outputs ?

S7Guy said:

Except for the new 318, the 300 series really aren't known for speed.

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I was led to believe the 318-2DP was being phased out, are you aware of a new 318 being introduced ?

The (relatively) new 317-2DP is quicker than the 318-2DP on all instructions except floating point arithmetic.

Yes I am looking for a less expensive alternative to the S7-200s for better processor spped. I will check the Cam controllers..

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Well, the cam controllers will definitely be more expensive. If the 200 is doing the job for you right now, you won't find anything cheaper in the Siemens world.

I was led to believe the 318-2DP was being phased out, are you aware of a new 318 being introduced ?

Click to expand...

Nope. That was a typo (I had 318 on my mind from an earlier conversation). The 317 is definitely the fastest 300 out there, and I might even choose it to replace some of my 416's for future projects.

Hi,

If your looking for a fast PLC have you looked at the VIPA SPEED7 offerings?

Something like 2mS per 100k instructions

...I don't have any idea on the price of them though but I'm told they are 'competitive' with the S7-300 series...

...just for info here's a benchmark test using the S7 318-2DP as the base speed....

A couple points of interest-
The FM352-5 is the fastest processor we have, the scan time is
1 microsecond- yes micro.
The scan display in Step7 will not read below 1ms, so an
empty program (although useless) will be below this.

JRW,

That's a nice piece of kit....pretty comprehensive instruction set too for something that's advertised as a boolean processor.

Reminds me somewhat of the old Modicon 984 'Logic Solver' module .... but on steroids!

Yes as hinted at by S7Guy and confirmed by JRW, if it's speed you're looking for, the FM352-5 is defintely the way to go. Despite the name, you don't even need a 300 CPU, you can use the FM3352-5 on it's own. The only limitation is the memory, if your job is too complex, you might run out of memory.

As to ease of use, if you start from zero, and try and learn it on your own, the learning curve is a bit like the North Face of the Eiger! However, 1) you aren't going to be doing it on your own, 2) the problems are entirely related to not doing things exactly the way you need to. Since I've already been down this road, we can solve that problem as well. After that, the thing really is quite straightforward. As far as cost is concerned, no way are you going to beat 200 series pricing, but for what it does, I think the 700€ it costs (if I remember correctly, I'm at home at present and haven't got a catalogue handy) is pretty fair.

If you have any specific questions come back and let me know. I'll be back online either Sunday evening or Monday (I've been on holiday the last few days).

One thing to remember when using the 300 I/o with the faster processors. The communications on the backplane is the limiting factor for hi-speed applications. The 400 I/o is much faster and more expensive. If it's speed you want, the boolean processor will boggle the mind. It is FAST.

Preeya

Just a quick note from a supplier point of view... The cost of a S7-200 is about $450 like you said. When you move up to the 300 series it gets MUCH more costly... Where you have to get a CPU, Power supply, I/O cards and Back plane... Aprox $3000 to $4000. Then the Software MicroWin aprox $500 for S7-200, where Step7 for the S7-300 around $2500....

Just to keep things on an even keel, Preeya said he (she?) needed 6 inputs and 5 outputs, the FM352-5 has 8 Inputs and 8 Outputs plus encoder Inputs (which can be used as 5 further normal Inputs if not required). As stated, the FM can operate standalone, without an S7 CPU and the package includes the necessary developement software. The only extra you need is a power supply and that doesn't cost the earth!

The only potential problem is limited memory, otherwise, if he needs this sort of speed, I can't see a better solution!

Thanks for all your replies.. I looked at the specs of FM352-5. It definitely seems like a good product.. although I may have to spend a lot of time learning how to program it..

The cost.. definitely a lot more than the s7-200, but is acceptable considering it has a scan time as low as 1 microsecond. I may have to present the whole situation to THE BOSS..

And oh! what kind of operator interface can I use with the FM352-5? Will the TP series work?

Garlic64 said:

When you move up to the 300 series it gets MUCH more costly... Where you have to get a CPU, Power supply, I/O cards and Back plane... Aprox $3000 to $4000. Then the Software MicroWin aprox $500 for S7-200, where Step7 for the S7-300 around $2500....

Click to expand...

Not that much more costly.
It uses plain 24VDC, no need for an additional power supply.
There is no "backplane" as such.
And STEP7 lite is even cheaper than MicroWin (dirt cheap really).

S7-300 is approximately 50% more expensive than S7-200 (my estimate).

Biggest problem is actually that the two series are very different. They dont compare 100% with each other.