Back to modernization
Legacy PLC.
Modernization / PLC check
Legacy PLC.
Your next step.
From an order number to a modernization concept. Check your controller and explore the technology and engineering work your upgrade may need.
Initial technical guidance · no registration
01Identify the system
02Explore a target
03Plan the project
JavaScript is required for the local check. You can also send your order number for a personal assessment.
Other ways to get in touch ↗Your initial assessment
One number.
A clear starting point.
Enter your CPU order number or try an example. Your result will include:
- Identification of the existing system
- A possible platform to plan around
- Relevant services and points to check
19 verified order numbers · 4 older families
Device source at Siemens ↗
Possible target direction
From the concept to a running machine
PLC software
HMI & communication
Commissioning
Before choosing the hardware
Initial engineering guidance, not a one-to-one replacement approval. The actual parts list follows a system assessment. Software, wiring and modules are not automatically transferable.
Turn the check into a project.
Include this assessment in an inquiry. I will review the existing system and propose a suitable modernization scope.
Opens an email draft. You review and send it yourself. Alternatively, copy the text and use another contact method.
Other ways to get in touch ↗View / copy inquiry text
More than a replacement part
The number is the start.
The system decides.
Replacing a legacy CPU is an engineering project. This check makes the first steps visible.
Understand the controller
Identify software, I/O, HMI and communication.
Develop the changeover
Plan the target system and software. Retain proven components where technically suitable.
Restore the functionality
Prepare, modify, test and hand over with an up-to-date backup.
Catalog scope and limitations
The starter catalog contains 19 specific CPU order numbers from SIMATIC S5, S7-200, S7-300 and S7-400. It does not cover every variant. Family hints inferred from number patterns are clearly marked. Target directions are our initial engineering guidance, not a Siemens replacement approval.
Siemens: S7-200 → S7-1200 ↗Siemens: S7-300/400 → S7-1500 ↗Siemens: controller selection ↗Siemens: S7-1200 G2 ↗
The S7-300/400 guide does not cover S7-400 migration in PCS 7. Manufacturer documents may be in a different language.
Sources checked: 12 October 2026