What Does Error "Failed to Download Expansion Instructions" Mean?

The Expansion Instructions are separate instructions that are not standard in the present PLC. These instructions can be downloaded to the PLC via CX-Programmer. You can select the instructions from the list on the left side and copy to the right side selecting the Set>> button. Alternatively you can remove the Instructions from the right side by selecting and clicking Remove>>.

It is important that the dipswitch of the PLC is correctly set up. It should be set for the "Expansion Instructions set by user". It is also important that the list of Expansion Instructions contains no empty fields, all should be filled and if necessary do this with a redundant instruction.