Siemens PLC software: which package your CPU needs, and why the project version decides what you can upload

The call usually starts the same way. Somebody bought a used machine with an S7-1200 in it, paid for STEP 7, plugged a laptop into the CPU, and TIA Portal said the configuration came from an earlier version and can't be uploaded, and offered to download instead.

Read that offer twice. Download means the empty project on your laptop goes into the CPU, and the only copy of the machine's program is gone.

So, the short answer first. Siemens PLC software for current hardware, meaning the S7-1200, the S7-1200 G2, the S7-1500 and the ET 200 CPUs, is STEP 7, and it runs inside TIA Portal. STEP 7 Basic covers the S7-1200. STEP 7 Professional covers all of it, the 1200 included. Older S7-300 and S7-400 lines can still call for classic STEP 7 V5.x, and the S7-200 and LOGO! have their own tools that never moved into TIA at all.

Picking the edition takes five minutes. The version is what eats the week.

Which Siemens PLC software goes with which CPU

Start from the CPU, not from the price list. Read the article number on the controller itself, or online in TIA Portal. Drawings on used machines lag. A CPU gets swapped during some breakdown, nobody touches the print, and years later it calls out a generation that isn't in the panel anymore.

What's in the panel	Siemens PLC software that programs it	Watch for
S7-1200, first generation	STEP 7 Basic or Professional	CPUs configured with firmware V1.0 don't open in V14 or newer
S7-1200 G2	STEP 7 Basic or Professional, V20 or newer	Not hardware-compatible with the first S7-1200; no older version programs it
Fail-safe S7-1200	STEP 7 Basic or Professional	STEP 7 Safety Basic comes with STEP 7, nothing extra to buy
S7-1500, ET 200SP and other ET 200 CPUs	STEP 7 Professional	Basic doesn't cover them at all
Fail-safe S7-1500, S7-300 or S7-400	STEP 7 Professional plus STEP 7 Safety Advanced	Safety Advanced is an add-on and requires Professional
S7-300, S7-400	STEP 7 Professional in TIA Portal, or classic STEP 7 V5.x	Moving classic projects into TIA Portal means migration, and V21 no longer migrates them
WinAC (PC-based controller)	STEP 7 Professional	Not covered by Basic
S7-200	STEP 7-Micro/WIN	Separate tool, not part of TIA Portal
LOGO!	LOGO! Soft Comfort	Separate tool, not part of TIA Portal

Match the Siemens PLC software to the CPU first. The version comes second, and it's the harder half.

Panels ride along. Both STEP 7 editions ship with WinCC Basic and WinCC Unified Basic, and those configure Basic Panels and Unified Basic Panels, nothing bigger. A Comfort panel on the same machine needs a higher WinCC edition. Good to know before somebody tells the plant manager one license opens the whole machine.

STEP 7 Basic or Professional

Basic is the smaller cut of Professional, and the controller list is where it stops: the S7-1200 and its I/O. That's the whole list.

Inside the box the two are closer than people expect. Both come with PLCSIM, with STEP 7 Safety Basic for the fail-safe 1200, and with WinCC Basic plus WinCC Unified Basic for the small panels. Professional adds the S7-1500 to PLCSIM, brings SINAMICS Startdrive for the drives, and opens every controller family past the 1200. Odd detail: Windows 11 Home is supported for the Basic editions only. Professional wants Windows 11 Pro or IoT Enterprise, Windows 10 Enterprise LTSC, or Windows Server.

Left, an S7-1200 CPU 1214C, which STEP 7 Basic covers. Right, an S7-1500 CPU 1511-1 PN, which needs Professional, like every ET 200SP CPU.

My rule is blunt. One S7-1500 or one ET 200SP CPU anywhere in the plant you look after, and you buy Professional. Basic looks like a saving right up to the day that CPU needs a change. Already own Basic? There's a Powerpack that takes it up to Professional. No need to start from zero.

When the quote for Siemens PLC software comes back, read the order numbers before you sign anything. In the 6ES7822 numbers, 0A is Basic and 1A is Professional. The letter right after that is E for a download or A for the boxed package, and from V21 the package ships on a USB stick instead of a DVD.

What it is	Download	Package
STEP 7 Basic V21, floating license	6ES7822-0AE25-0YA5	6ES7822-0AA25-0YA5
STEP 7 Professional V21, floating license	6ES7822-1AE25-0YA5	6ES7822-1AA25-0YA5
STEP 7 Professional V21 Combo (TIA Portal and classic STEP 7)	6ES7810-5CE18-0YB5	6ES7810-5CC18-0YA5
Powerpack, Basic V19-V21 to Professional V19-V21	6ES7822-1AE23-0YC5	Not offered
Upgrade, Basic V11-V20 to V21	6ES7822-0AE25-0YE5	6ES7822-0AA25-0YE5
Upgrade, Professional V11-V20 (or Combo V17-V20) to V21	6ES7822-1AE25-0YE5	6ES7822-1AA25-0YE5
Software Update Service, Basic	6ES7822-0AE00-0YY0	6ES7822-0AA00-0YL0
Software Update Service, Professional	6ES7822-1AE00-0YY0	6ES7822-1AA00-0YL5
Software Update Service, Professional Combo	6ES7810-5CC04-0YY2	6ES7810-5CC04-0YE2

Siemens PLC software order numbers for V21. They change with each release, so check the number against the version you're actually quoting.

One trap with the Combo: the plain Professional Software Update Service doesn't upgrade it, the Combo has its own SUS. And when classic STEP 7 projects for S7-300 or S7-400 are still part of the job, the Combo is the one to buy: it licenses both, and both run side by side.

The version on the CPU matters more than the edition

Buying the right Siemens PLC software doesn't help much if it's the wrong version. An S7-1200 or S7-1500 knows which TIA Portal version downloaded it last, and to pull that program back into an editable project your laptop needs the same one. Not newer. The same. From V14 SP1 on there's no slack at all: a CPU loaded from V17 uploads in V17, and V18 and V21 both refuse it. The overlaps that exist are all old ones, V14 into V14 SP1, V13 into V13 SP1 and a few V11 and V12 combinations.

What works with any version is Online & diagnostics through Online access. Article number, firmware, the diagnostic buffer, the operating mode: none of that cares which version loaded the CPU. On an unknown machine it's the first thing I open, before anything with upload or download in its name.

Project loaded into the CPU with	TIA Portal version that uploads it	Notes
V11	V12	Software only, in compatibility mode. A hardware configuration from V11 can't be uploaded at all
V12	V12, V13, V13 SP1	Software only, no upload as a new station; V13 only in compatibility mode
V13	V13, V13 SP1	V13 SP1 only in compatibility mode
V13 SP1	V13 SP1	Same version only
V14	V14, V14 SP1	The last overlap
V14 SP1	V14 SP1	Same version only
V15	V15	Same version only; V15.1 won't upload it
V15.1	V15.1	Same version only
V16	V16	Same version only
V17	V17	Same version only
V18	V18	Same version only
V19	V19	Same version only
V20	V20	Same version only
V21	V21	Same version only

Uploading from S7-1200 and S7-1500 CPUs. Past V14 SP1 it's the same version or nothing. Online & diagnostics works in all of them.

A failed upload writes nothing to the CPU, so trying is safe. Taking the download that error message offers is not. After a download the CPU carries your project, and the builder's program is gone. No undo on the controller side.

Even with the right version, a couple of things bite. Upload device as new station brings the station name with it, and if your project already holds a station with that name, the upload aborts, so rename yours first. Blocks the builder protected with know-how protection come across locked, and without the password you won't see the logic inside. Once the upload goes through, take a Backup from online device too. It's a 1:1 copy with date and time that you can't edit but can put back into the CPU later. Costs a minute.

Finding out which version loaded the CPU

If the builder sends a project or an archive, the file extension answers it: .ap17 or .zap17 is V17, .ap15_1 is V15.1, and so on. That email is the cheapest step in this whole business. Send it first.

No project and nobody to ask, then it gets narrower, not easy. Firmware sets a floor. An S7-1200 with V4 firmware was loaded from V13 or newer, a G2 from V20 or newer, and that's all the firmware will tell you. Next you try the upload in the version you have and read the upload preview, which checks the version before anything moves. A mismatch means installing the matching version, and on a used machine that's nearly always an older one.

Older versions can share the laptop. V21 installs in parallel with STEP 7 V13 SP2 through V20 and with classic STEP 7 V5.6 or newer. V13 SP1 isn't on that list. A CPU loaded from V13 SP1 means a separate PC or a virtual machine. Check the supported Windows for each old version before it goes on a new laptop; an old release that doesn't list your Windows is a job for a virtual machine.

The order that doesn't cost you the program. Everything above the red box is safe to try.

Say you inherit a line with two 1214C CPUs. Online & diagnostics shows a 40 right before the -0XB0 in both article numbers and V4 firmware, so the floor is V13. You're on V21, and the upload preview says the configuration came from an earlier version, without saying which. You install V16. Same answer. V17 goes through. Upload, save, archive, take the online backup, then close the laptop.

Now there's a choice to make. Keep maintaining that line in V17, or open the project in V21 and let it make an upgraded copy. Download from V21 once and the CPU carries V21 until someone downloads from another version, and whoever needs to upload it after you needs V21 too. I leave machines on the version I found them on unless something forces the move. Every upgrade raises the version that can upload that CPU, and going back takes the old project file.

Opening old projects in V21

Opening an old project file is a different problem from uploading, and a friendlier one. A newer TIA Portal opens an older project and upgrades it into a copy; the original file stays as it was. Nothing in TIA Portal takes a project back down a version. Customer runs V19? Build it in V19 from day one.

V21 takes V14 through V20 projects directly. A V13 SP1 or SP2 project has to go through something between V14 and V20 first, and V20 is the obvious pick since it upgrades everything from V13 SP1 to V19. Anything older, V11, V12 or V13 without a service pack, has to be saved and compiled in V13 SP1 or SP2 before a later version will touch it. Use SP2 if you can; it's the oldest release that shares a PC with V21. If the upgrade still refuses, rebuild everything there first: Compile > Hardware (rebuild all), then Compile > Software (rebuild all blocks).

Two more that stop an upgrade cold. Every option package in the project has to be installed at the new version. A project with Startdrive in it won't upgrade on a PC without the matching Startdrive, and TIA refuses with a message that necessary products are not installed." Then there's the S7-1200 configured with firmware V1.0, which V14 and newer won't open. Change the configured firmware in V13 SP1 first, or add a new V4.0 CPU offline and copy the program across.

Every route ends in V21, and V21 only opens V14 through V20 projects directly.

Licenses, the trial, and what a key covers

Licensing for Siemens PLC software runs in one direction. A STEP 7 key covers its own version and everything older, so a V21 license runs V17 or V16 without complaint, which is exactly what the upload problem needs. It never works forward. A V16 key won't open V21; that takes an upgrade license or the Software Update Service, which delivers each release as it comes out. The keys are floating: one license moves between laptops, one at a time.

The trial is the full installer, not a cut-down edition. As a registered customer you download STEP 7 V21 with Safety, PLCSIM and WinCC and use it for 21 days. After that it needs a license key. Older versions have their own trial downloads going back to V13, which is how the V17 in the example above gets onto a laptop. Plan for the size: about 8.1 GB for the main image and another 3.1 GB for the second one with the hardware support packages. When a newer module shows up as unknown in the hardware catalog, a missing support package is usually why.

Twenty-one days is plenty to pull a program, archive it and look around. It won't run a plant. And sort out the account registration before you're standing in front of the machine. Siemens also sells TIA Portal as an annual subscription and as a cloud instance billed by the hour, month or year. Fine for a one-off job. I'd still rather have a key on the laptop that lives in the truck.

PLCSIM comes with both editions; in Basic it simulates the S7-1200 only. PLCSIM Advanced installs along with it on V21 but needs its own license, and since V8.0 it takes the G2 too.

S7-300 and S7-400: TIA Portal or classic STEP 7

Here the Siemens PLC software question has two answers. STEP 7 Professional programs the S7-300 and S7-400 inside TIA Portal. The catch is the project: many running 300 and 400 lines were built in classic STEP 7 V5.x, and TIA doesn't open those, it migrates them. V21 has stopped doing even that. Migration now takes the Migration Tool plus TIA Portal V20 or earlier, and then an upgrade to V21.

Migration has conditions of its own. Licensed classic STEP 7 V5.4 SP5 or newer and every option package the project uses have to be installed where the migration runs, and a very old V5.x project gets recompiled in V5.4 SP5 or newer first. Hardware stays behind unless you tick Include hardware configuration, and then every module has to exist in the TIA hardware catalog, which covers modules that were orderable and not yet discontinued by 2007. One missing module and the migration aborts, unless a GSDML file can stand in for it.

The one that burns people: the consistency check compiles the blocks, and that compile resets the instance DBs of technology blocks to their default values. PID blocks included, recipe data blocks too. Save those instance DBs before the check and copy them back after. Blocks protected in V5.x with KNOW_HOW_PROTECT or S7 Block Privacy come across unreadable, and TIA can't lift that protection. The one exception is protected SCL blocks with their source, which come across editable. Remove the protection in V5.x first, or live without those blocks.

On a line that runs fine, I keep maintaining it in classic STEP 7 and migrate nothing. The Combo license covers both, and they install side by side. Also, a CPU with only an MPI or PROFIBUS port won't talk over a plain Ethernet cable; the laptop needs an adapter for that.

Replacing an S7-1200: read the article number first

A replacement CPU is where Siemens PLC software and hardware get tangled together. Between generations, S7-1200 firmware only upgrades from V1.x to V2.x. V2, V3 and V4 each need their own hardware, so a V3 CPU can't be flashed up to V4. Look at the two digits right before -0XB0. On the 1212C and 1215C relay-output versions, for example, 31 is V3 hardware and 40 is V4. Every G2 CPU number ends in 50-0XB0.

Same model, three article numbers: the two digits before -0XB0 give the generation.

Match the article number and the swap stays a hardware job. Change generations and it turns into a software job: device change in the project, compile, download. So you need the project and a TIA version that works with it before the new CPU goes in, and after the download that CPU carries your version. The G2 goes a step further. Its hardware doesn't match the first S7-1200, the existing code converts with minor changes, and it needs V20 or newer.

Siemens PLC software, the short version

What you have	What to install
S7-1200, project file in hand	STEP 7 Basic at the file's version, or a newer one that can upgrade it (newer makes an upgraded copy)
S7-1200 in a machine, no project	STEP 7 Basic at exactly the version that loaded the CPU
S7-1200 G2	STEP 7 Basic V20 or newer
Any S7-1500 or ET 200SP CPU in the plant	STEP 7 Professional, or a Powerpack if you already own Basic
Fail-safe S7-1500	STEP 7 Professional plus STEP 7 Safety Advanced
S7-300 or S7-400 running classic STEP 7 projects	STEP 7 Professional Combo, classic and TIA Portal side by side
Learning, no machine yet	The 21-day trial, PLCSIM included

Frequently asked questions

What Siemens PLC software do I need for an S7-1200?

STEP 7 Basic in TIA Portal, or Professional if bigger CPUs are in the picture too. A G2 needs V20 or newer. On a CPU that's already running a machine, sort out the version first: without the project, the program only comes out in the exact version that loaded it.

Can STEP 7 Basic program an S7-1500?

No. Basic covers the S7-1200 family and nothing past it. S7-1500 and ET 200SP CPUs need Professional. If you already paid for Basic, the Powerpack gets you there without buying a new license from scratch.

Can I open a newer TIA Portal project in an older version?

Not in any supported way. Opening a project in a newer version turns it into an upgraded copy, and the older version can't read that copy. If the customer runs V18, do the work in V18 from the start, and keep the original of anything you upgrade.

Is there a free version of Siemens PLC software?

For TIA Portal, the free option is the 21-day trial, which is the full installer for registered customers. After that it needs a key. The trial downloads for older releases are also the normal way to install an older version your newer key already covers.

Why does TIA Portal say the configuration was created with an earlier version and cannot be uploaded?

The CPU was loaded from an older TIA Portal version than the one you're running, and S7-1200 and S7-1500 CPUs don't upload across versions. Install the version that matches, which your key covers, and upload there. Don't accept the download the message offers. It replaces the program in the CPU.

If the CPU is the part that failed

Sometimes the Siemens PLC software is fine and the controller isn't. IQElectro stocks S7-1200 CPUs like the 1212C 6ES7212-1AE40-0XB0, the 1214C in DC/DC/DC as 6ES7214-1AG40-0XB0 and AC/DC/RLY as 6ES7214-1BG40-0XB0, and the 1215C 6ES7215-1AG40-0XB0, plus S7-1500 CPUs including the 6ES7511-1AK02-0AB0, 6ES7515-2AM02-0AB0, 6ES7516-3AP03-0AB0 and the fail-safe 6ES7516-3FN02-0AB0, all with a 2-year warranty. We sell hardware, not licenses. IQElectro isn't a Siemens authorized dealer, so the STEP 7 key comes from your Siemens distributor. Send us the article number off the CPU, not off the drawing, and we'll tell you what's on the shelf.