STEP 7 and RSLogix5000

DamianInRochester

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Not looking for stone throwing or even opinions on this one. More so just looking for some tangible, verifiable facts.

When it comes to Step7 and RSLogix5000, in general, what specifically can be done in one that can't be done in the other? Can anyone cite specific examples of something that can be done in one, that would be monstrous to accomplish the same thing in the other?

It would be nice to separate "taste" from actual "functionality"

For staters, I'll throw out there that Siemens will not work well natively with EthernetIP and AB will not work well natively with Profinet.

And by "native" I mean you do not require a 3rd party device to make it happen.

Another example someone mentioned (unrelated to AB - Siemens) is that GE has double redundancy.

What does one "got" that the other "don't got"?
 
As you may know, various European countries are at risk of financial meltdown and this may result in redundancies of the job kind.
 
from what I remember

here are a few differences:

Siemens:
  1. There is a central software (S7 Manager) for Siemens which is a nice feature. You can see all of your PLCs, HMIs, etc in one software, and when you try to edit the settings, it finds the appropriate software for editing, such as the ladder editor for PLC.
  2. you can do partial downloads. for example, you can choose to download just one DB that you made changes to, or an FC, etc.
  3. Siemens uses addressed based tagging which can get you into trouble. For instance, say you have a UDT with 30 elements, and then you decide that you want to add one more element... you're screwed unless you left spare room in the UDT. If you used that UDT in a DB, everything in that DB will shift by the size of the element you added. This WILL cost you major time if you don't remember.
  4. Siemens is much more confusing and destructive when doing an upload. I saved an online version of a DB once, only to find that all of my tags were now DBX0.0, etc. This too will cost you BIG time, not only in changing the DBs but also anywhere in the code that you used that DB will be shifted now.
  5. horrible SimaticNet software
  6. great support
Rockwell:
  1. completely tag based. No messing around with addresses.
  2. easier to configure communications through RSLinx
  3. easier setting up PLC to PLC comms
  4. no partial download
  5. great support
Please keep in mind that the last S7 project I did was with version 5.2 in 2004 or so. It may be worth mentioning that until version 16 of RSLogix 5000, I would've chosen Siemens, but now Rockwell has addon instructions (welcome to the 21st century).

There are more things but it's back to work for me.
(y)
 
3. Siemens uses addressed based tagging which can get you into trouble. For instance, say you have a UDT with 30 elements, and then you decide that you want to add one more element... you're screwed unless you left spare room in the UDT. If you used that UDT in a DB, everything in that DB will shift by the size of the element you added. This WILL cost you major time if you don't remember.
4. Siemens is much more confusing and destructive when doing an upload. I saved an online version of a DB once, only to find that all of my tags were now DBX0.0, etc. This too will cost you BIG time, not only in changing the DBs but also anywhere in the code that you used that DB will be shifted now.
Both of these problems with shifting addresses are because you have absolute address priority.
Change to symbolic address priority.

edit:
And to the original question, I think there is very little that absolutely can be done in one platform and not in the other.
 
Last edited:
I can't say that I like over the other but here's 2 of the top of my head:

Siemens allows for greater address manipulability.

Siemens does not automatically convert datatypes. It gets really old, really fast when you have to convert INT -> REAL and back again etc.
 
Both platforms have their advantages and the more I've had to do with Siemens the more I can appreciate some of the techniques that really save time. But the kicker for me are strings and indirect addressing let alone indirect addressing on strings.

Jesper thanks for the tip on "Both of these problems with shifting addresses are because you have absolute address priority. Change to symbolic address priority."
 
I can't say that I like over the other but here's 2 of the top of my head:

Siemens allows for greater address manipulability.

Siemens does not automatically convert datatypes. It gets really old, really fast when you have to convert INT -> REAL and back again etc.


I forgot about that. It gets old really fast.
 

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