OT: Can someone explain Rockwell versioning system

This is a bit of a rant lol, my first 5 years as a systems integrator was using Siemens, then I came to the dark side of Allen Bradley / Rockwell. It baffles me their software packages are tied per version firmware. It is a strange model given that Rockwell PLCs are so expensive. As someone who has used Siemens, I don't find RSLogix and its tools superior at all.

The thing with siemens is that you use either Step7 or Tia, and call it a day. No need to buy another version because of a higher firmware exists.

Can someone explain if there is good reasoning behind their logic, or is it pure money, money, money.........money?

I hate Rockwell, but you'll find that TIA Portal is a step in Rockwell's direction. Step7 though was great.

The reasoning with Rockwell does seem to be more money and little value. However, as you will see, people will disagree and will go to war over Rockwell.

You should bring up the comparable price of the software packages next, seeing people deny that Rockwell is about 4 times more expensive than Siemens TIA Portal because you can get a "ladder only" license is really funny. And don't get me started on the reliability of their kit.

TIA Portal is a step in Rockwell's direction

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This is true on the software version side, but TIA Portal V15.0 will support every CPU version down to V2.6 of the S7-300 family, and every CPU version of the S7-1500 and every CPU down to V2.1 of the S7-1200.

With Rockwell, your CPU firmware must match the version of software. If you want to upgrade the software, you must upgrade your CPU firmware as well.

STEP 7 Classic has 5 major versions, and the STEP 7 in the TIA Portal Platform has 6 major versions, and Rockwell has 31 major versions.

Each version STEP 7 covers a wide range of CPU firmware versions, each version of RS Logix 5000 only covers one version of CPU firmware.

One interesting thing about S7 CPUs, is that in general, your project can contain an older version than what is actually installed. This is great in the case where you buy a new CPU to replace a defective one: the firmware doesn't have to match, it only has to be the same or newer.

TIA Portal is a step in Rockwell's direction

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I think one of the reasons is that they are trying to cater to more US companies to make it look like RSLogix and Studio5K.

Yes, I do enjoy Step7 more than Tia, having everything crammed in one window was really a bad design for user experience, but still Siemens software and firmware is solid.

Rockwell CPUs have no diagnostic buffer, at least I haven't seen one. Maybe someone more experienced can provide info on that.
Finding a tag in a big program is a pain unless you know which program is under, don't even get me started with the compare function is pretty much useless if I try to compare a V20 with a V30 program. Even so comparing same version projects is so freaking slow.

Cross reference in siemens is better for sure, you can go to in the same block, something you can't really do with rslogix in the same routine.

In Rockwell eveything has to have a middleware, rslinx, dataserver, etc. In siemens you can have just a plc and an hmi and go to town.

Pretty much feature per feature siemens wins in most areas.
Price of a Controllogix 15K, price of a S7-300 2K.

As someone who learned Siemens first I don't understand why people have hard time getting it.

having everything crammed in one window was really a bad design for user experience

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You can "float" the editors into separate Windows... But, yeah, getting to the properties of an object in a floated window is a pain.

One interesting thing about S7 CPUs, is that in general, your project can contain an older version than what is actually installed. This is great in the case where you buy a new CPU to replace a defective one: the firmware doesn't have to match, it only has to be the same or newer.

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Yeah none of that rubbish, can't open project because you don't have version so and so. Unless of course you have all previous versions installed.

Just open hw config, and change cpu firmware version. I don't think people that never used siemens realize how much of a pain it is to deal with all those rslogix version packages.

Just keep in mind it all boils down to:


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$


Everytime Rockwell can create a new version everyone that can't afford their T.C contract will have to buy the new version at full price, or find a way to budget the annual contract fee.

Each piece of Rockwell software gets installed in its own directory within the main Rockwell directory in program files. Each version is its own install.


You MUST have the correct MAJOR revision to access a particular PLC's program. The firmware major revision has to match.


There is an exception to the above rule: 20.01 and 20.03 are not compatible minor revisions due to firmware security features on 20.03. Instead, install 20.04 which "fixes" this issue.


I'm not sure after about 27, I have not used Rockwell for a long time for anything meaningful.


The catalog numbers of all the software is very confusing as well.

sigmadelta said:

...but TIA Portal V15.0 will support every CPU version down to V2.6 of the S7-300 family.

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Not sure about that. My version of V15 does not have CPU-318, and many of of the CPUs only show newer versions.

mister x said:

Not sure about that. My version of V15 does not have CPU-318, and many of of the CPUs only show newer versions.

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I never did this on Tia, but on step7 you could just import new components with catalog, I remember having to import 317-T cpu like that. Of course newer firmware is always the best choice. I'm sure you can probably still open projects.

In Rslogix/Studio you can't even open a project without correct firmware matching rslogix/studio version.

mister x said:

Not sure about that. My version of V15 does not have CPU-318, and many of of the CPUs only show newer versions.

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What I was told back at the beginning of the Portal days was that it included almost everything they considered "active product" as of Oct 1, 2007. I think the 318's were phased out a bit before that, because it was a confusing jumble of a 400 in a 300 shell. Portal never supported the 400H system, the 300T's, and a few of the option packages like PDiag and Hi-Graph.

With the latest releases they've started to walk that support back somewhat. They dropped support for the older panels (basically, everything supporting by WinCC Flex), but I haven't seen any PLC HW vanish yet.

Horses for courses.

sigmadelta said:

This is true on the software version side,

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Sorry, I was in a bit of a rush. My comment meant that to access a PLC programmed with V14 of TIA you have to have that version installed.

However, if you have the source code you can just use V15 to program that CPU without having to faff around.

Not sure about that. My version of V15 does not have CPU-318, and many of of the CPUs only show newer versions.

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The CPU-318 was really an S7-400 in disguise.

If you are ever in doubt about compatibility, check the following:

Siemens Compatibility Tool

Rockwell Compatibility and Download