A squick set of pointers and hints for the Upgrade Migration from a compact Melsec PLC to a different Melsec PLC Options.

Traditionally – the following migration paths are automatically accomodated (For the most part);

  •      Melsec-FX is being migrated to Melsec-iQ-F (Compact to Compact)
  •      Melsec-A,Q are being migrated to Melsec-iQ-R (Modular to Modular)

​However, it is possible to move from FX to iQ-R – but with some points to note:


  1. Many Migration functions will NOT be automatically transferred – manual transfer or alterations (and in some cases even program engineering) will be required.
  2. The IO of the iQ-R must be applied and configured such that it complies to the IO of the FX CPU and modules.
  3. Any intelligent function cards. Modules and adaptor configuration settings – whether via the configuration tool or via PLC program – will be void and needs to removed and reconfigured.
  4. Any CPU special registers (SD) and special registers (SM) will have to be remapped manually.

In conclusion –

Only the basic PLC logic can be recycled. (this is why FX is traditionally transferred to iQ-F and not iQ-R).