Siemens and Allen-Bradley

A few European customers have asked if we would convert our controls from Allen-Bradley to Siemens. Right now our system is controlled by either a 16 Rack PLC5/30, 504's or 505's and a PKTX module in the desktop for the 504 or 5/30 using DH+. I have also designed a couple of systems using Compact Logix 35E.
Usually a dozen analog in and out (PID control) and 40/50 misc regular i/o.

I have some Siemens experience but not a lot.

I am considering contacting our local Siemens rep and possible buying 4 modules (2 analog in/out and 2 regular in/out), software, power supply, etc. and start experimenting.

I am not really worried about normal I/O, but I have heard the PID loop controls in Siemens can be a bit complicated.

I would also like the Siemens processor to support ethernet like the 505 and 35E.

Question: Is the the S7-300 my best bet here.

I will be contacting our local rep and maybe he might be my best source but I am hoping for a little heads up info here.

Thanks.

Your customers are probably NOT thinking "S7-200" when they suggest "S7". It is not uncommon over here, but not nearly as popular as in the US. So yes it sounds like an S7-300.

Approx 12 analog + 50 digital i/o. Ethernet capability.
I suggest the S7 315-2PN/DP or the S7 317-2PN/DP.
Both have Profibus and Ethernet capability.
315 is with regard to performance and memory size equal to a PLC5/30, SLC5/04 or SLC5/05.
317 has approx 4 times the performance and memory as the 315.
If you want to go cheaper than a 315, then consider a 314 + an additional Ethernet CP.

On to the obvious next question:
Is there a way to port AB code to S7 code automatically ?
Answer: NO.
The good news is that pure AB ladder translates pretty well to pure S7 ladder. Only it has to be typed in manually.

If you have other questions about how programming S7 compares with programming AB, then do ask here.
It can be a tough thing to find out by one self.
I went from S5 to AB, and then from AB to S7, so I have a good idea about their respective strengths, weaknesses and quirks.

By the way, what are using the desktop PC for ?
I can give you a couple of suggestions what a similar PC application with S7 may look like.

Thanks Jesper,

The S7 315 is something that I will be checking in to. I am starting to pour over web sites and gathering as much info as I can.

I write custom code using Visual Basic to interface with the A-B processors. I use software by Automation Solutions for my interface.

That will be another thing I must check out is whether the Automation Solutions software supports the S7.

Well, I can tell you that there is no ActiveX type library for the Ethernet connection to the two mentioned CPUs. (including Automated Solutions !).
The two CPUs mentioned only support the "S7" protocol over ethernet, and noone has ActiveX software that allows connection via that protocol.
Your best bet is to use OPC with "Simatic Softnet S7 Lean".

Alternatively Rothenbacher makes an ActiveX library (surprisingly cheap). But it uses the "RFC1006" protocol (aka "ISO on TCP").
For that you need an additional Ethernet CP card (you cannot use the onboard Ethernet on the 315 2PN/DP or 317-2 PN/DP).

Also, Deltalogic makes a good DLL library (not an ActiveX library) ACCON-AGLINK that should work also with "S7" protocol.

We've gone through a similar adaptation. I strongly recommend that you get some training on the Siemens system. This platform is very powerful, but the set up and programming is definitely not intuitive. The same is true of the software. On top of that, the documentation is, in my opinion, terrible. It is detailed to the point of obscuring useful information, it takes three or four manuals for everything, and is not well organized.

Siemens is the only platform we have ever programmed where we couldn't sit down and figure things out "on the fly". We have one system under our belts, and we are about to do our second system. I have included classes in my budget to make this time around a lot simpler.

My question is "Is it worth changing you entire control scheme over to a different platform for a one-up?" I try to stay away from doing conversions because it typically ends up costing more than it was worth to do. You not only have the time that you have to spend in redesigning your controls but also then have to provide support for a platform that you are not familiar with. We made three systems back in the early 90s that used Red lion Indicators and now cringe whenever there is a troubleshooting call because now one really remembers how they work.

Just my .02

Bob

Thanks Tom for your input.
Bob, I would love nothing more than staying with the AB's. The problem is my company is doing more and more international systems and we have no choice if we are to get the business.

Our quotes will probably be quite high with training, countless programming hours and such. If the customer is willing to pay, no problem.

Jespers comment about no activex interface concerns me. Looks like I will have a lot of rewriting in my VB code as well.

When you open up a can of worms, go fishing.

Mark,

Here's a suggestion, call your local Siemens rep. and get
their application engineer in to go over Step7 with you.
This sounds like something Tom didnt do. He is right, if you load Step7 and start banging on the keyboard because "I have programmed Automation Direct for 20 years". You will have trouble. Its not structured the same way.
Once you understand FB's, FC's, DB's, UDT's- you will love it.
Its a hell of a powerful system and I would put it up against anything. But do some reading and get a knowledgeable rep to spend a day with you.

Jespers comment about no activex interface concerns me

Click to expand...

Well, there IS an ActiveX from Rothenbacher, but you have to add an Ethernet CP in order to use.
You can then get a 'regular' S7 315-2DP. That one does not have the onboard Ethernet port.
The price of the 315-2PN/DP is pretty much the same as a 315-2DP + Ethernet CP.

I am more worried about that Rothenbacher looks like a very small firm to me. The documentation for the ActiveX library appears a little 'thin'.
I would download the demo of the library and try it out with the mentioned 315-2DP + Ethernet CP.

Only want Siemens???....!!!

We did alot of work in ASIA the past couple of years.
During the contract talks many of the companies made
it clear only Siemens controls was used at there
locations. When we arrived for start up several
other vendors were there. Some from the U.S.
and from other countries like Germany , Italy ,
Japan , etc. We the noticed alot of the controls
were Allen-Bradley and some Mitsubishi! Plus the
older machinery had AB controls. It's CRAZY....