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Legacy PLC Migration & Retrofit

Legacy S7-200, S7-300, S7-400 and Moeller or Telemecanique controllers reach a point where spares dry up and the original programmer is long gone. The risk in these projects is rarely the conversion itself — it is the undocumented logic nobody can explain, which is why the audit comes before anything is rewritten.

What this covers

  • Code audit — reading and documenting existing STEP 7 v5.x logic, including the blocks nobody has touched in fifteen years.
  • Block conversion — STL and LAD blocks and data blocks rebuilt in TIA Portal SCL and LAD rather than machine-translated.
  • Network migration — Profibus-DP to Profinet planning, bridging where a staged cutover is needed.
  • HMI redesign — obsolete WinCC flexible panels rebuilt in WinCC Unified or Basic.
  • Schematic update — revised terminal assignments, 24 VDC control distribution and terminal block layouts.
  • Staged changeover — sequencing that keeps the switchboard in service, with fallback at each step.

What you receive

  • Existing system audit report with the recovered logic documented
  • Converted TIA Portal project, commented and structured for future maintenance
  • Profibus to Profinet migration plan with outage requirements identified
  • Updated control schematics and terminal schedules
  • Commissioning and changeover procedure with rollback steps

Standards and references

Converted logic is structured to IEC 61131-3, with network migration to the applicable Profinet and Profibus specifications and schematics to IEC 81346 reference designation practice.

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Need this scoped?

Tell us about the switchboard, the source configuration and the specification you have been handed.

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