dottc - 2018-06-27

I am trying to log onto my TTC VisionPlus PLC and program using codesys V2.3. When i log in it gets to the end and displays this error:

The last online service has not been executed correctly!
Servive number: 47, Error number: 80
File'rev4_slave.txt' could not be written.

Does anyone know what this error represents or knows if it's a codesys problem or plc problem?

Thanks