If you’ve been researching the Siemens S7-1200 G2 vs G1, you’ve probably seen a lot of articles saying the same thing:
“G2 is faster, more powerful, and the obvious upgrade.”
That’s not wrong — but it’s also not the full story.
From an engineering perspective, choosing between G1 and G2 is not about which one is better, but which one fits your project reality.
This article will walk you through the real-world differences, hidden risks, and practical decision rules — so you don’t make an expensive mistake.
1. The Simple Truth (Skip Everything Else If You Want)
New projects → Choose G2
Existing systems → Stay with G1
Retrofit projects → Do NOT directly switch to G2
If you understand this, you already avoid 80% of common mistakes.
Now let’s explain why.
2. Performance: Better, But Often Irrelevant
Yes, G2 is clearly more powerful:
Faster processing speed
Larger memory
Better handling of data and communication
But here’s the reality:
Most industrial applications:
Digital I/O control
Simple sequencing
Basic automation logic
�� These do not need more performance
Engineering takeaway:
Performance is rarely the deciding factor unless you are doing:
Motion control
Data-heavy systems
Advanced communication
3. Compatibility: The Biggest Trap
This is where most online articles mislead you.
❗ G1 and G2 are NOT compatible
That means:
I/O modules cannot be reused
Expansion modules cannot be reused
Hardware dimensions have changed
Real-world impact:
Switching from G1 to G2 means:
Rebuilding your control cabinet
Rewiring I/O
Reconfiguring hardware
Retesting the entire system
�� This is NOT an upgrade — it’s a system redesign
4. Software Migration: Not Plug-and-Play
Using TIA Portal, many assume:
“I’ll just open the old project and switch CPU.”
That’s not how it works.
What actually happens:
Hardware configuration must be rebuilt
I/O addressing must be verified
Communication needs reconfiguration
Testing is required
Time cost:
Small project: 1–3 days
Medium project: several days
Large project: 1+ week
5. Communication & IT: A Shift in Direction
G2 is designed for:
Ethernet-based systems
IT/OT integration
Remote access
IIoT / data-driven environments
This is great if you need:
MES integration
Cloud connectivity
Remote diagnostics
But…
Older systems using:
Legacy communication
Older field devices
�� May require extra effort to integrate
6. Function Changes: Not Just “More Features”
G2 introduces:
Improved motion control
Modern diagnostic tools (like NFC)
But also:
Changes in how some functions work
Different engineering workflows
Reality in the field:
Experienced engineers often feel:
“This doesn’t behave like the old system.”
There is a learning curve
7. Real Engineering Scenarios
Scenario 1: New Machine / New Line
✅ Choose G2
Why:
Future-proof
Better integration capabilities
Longer lifecycle
Scenario 2: Existing Production Line
✅ Stay with G1
Why:
No redesign needed
Spare parts already available
Lowest risk
Golden rule:
If it works, don’t touch it.
Scenario 3: Retrofit / Upgrade Project
⚠️ Be very careful
Switching to G2 means:
Hardware redesign
Software adjustments
Downtime risk
�� Often better options:
Stay with G1
Or jump to a higher platform (like S7-1500)
Scenario 4: Digitalization / Smart Factory
✅ Choose G2
Why:
Better networking
Easier integration with modern systems
8. Common Mistakes (Avoid These)
❌ Mistake 1: Treating G2 as a drop-in replacement
It’s not.
❌ Mistake 2: Ignoring cabinet size changes
It may not physically fit.
❌ Mistake 3: Assuming software migration is easy
It isn’t.
❌ Mistake 4: Mixing G1 and G2 hardware
Impossible.
❌ Mistake 5: Breaking your spare parts strategy
G1 and G2 cannot share inventory.
9. Final Decision Guide
Use this quick checklist:
Want stability and minimal risk? → G1
Starting from scratch? → G2
Upgrading an existing system? → Think twice before G2
10. Final Thought
G2 is not “better” in every situation.
It’s simply:
More modern
More powerful
Less compatible with the past
And in industrial automation, compatibility often matters more than performance.
If you're unsure which option fits your project, feel free to reach out — choosing the wrong PLC platform can cost far more than the hardware itself.
Need help choosing between G1 and G2 for your project? Contact us for expert advice.
Email: info@bxlyplc.com
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