Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.xx

I have some networked Citects and a ModbusPlus network of IODevices. I am receiving some hardware errors on my IO Server, but I cannot find the cause of these. Interestingly, a stand alone Citect connected to the same ModbusPlus network does not report any of these communications errors. 

The MBPlus protocol software interface essentially emulates a NetBIOS network protocol. Citect also uses NetBIOS for communication between Citect Servers and Clients. It is possible for the MBPlus NetBIOS and the standard NetBIOS interfaces to clash. This clash results in errors such as "Error Data Size to big" and "Error: Address is out of range". or possibly "response is bad or garbled".

This problem only occurs on a networked Citect system and only if you are using the NetBEUI network protocol. To overcome it, change your network protocol to IPX/SPX and remove NetBEUI completely.