The target read/write data address does not match the actual address

[xiaojujuovo]

When I write MW2 123, on the PLC it is MW4 becomes 123. MB2, the PLC becomes MB5. But there is no problem with writing BOOL

[mycroes]

I think you might be writing an int instead of short, which means you're writing 2 registers at the same time. Not sure how that affects MB2 / MB5 though. If you provide more information (code, PLC type) we might be able to assist.