Who knows a profibus logger (I suppose it wil be a pc-tool) that can log profibus faults during multiple days. Purpose will be to see if slaves go down, if there is electrical interference on the bus, if bus voltage is dropped down etc.
The Profitrace from procentec
The distributor in Belgium is Bintz
It is the best tool available on the market (personal opinion) for PROFIBUS diagnose. But I recommend that you also follow the PROFIBUS training before you buy this tool.