A knowledge blind spot in Mitsubishi PLCs is the reading backup of file registers R and ZR. It becomes quite simple once you know it, but if you don’t, it can be quite perplexing. A customer created a new device, but with over a hundred models, they wanted to import all parameters from the old device to avoid the hassle of manual input. However, the device parameters are stored in file registers, and even when selecting ‘read all’ in the reading program, the model parameters were not retrieved, meaning the data from the file registers was not read. At this point, we just need to know that the data from the file registers exists in standard RAM, so we need to select standard RAM in the object storage area during reading to access the data from the file registers and transfer it to the new PLC.
Therefore, when using Mitsubishi PLCs, we must remember to select standard RAM to read the backup of the file registers.