Applies To:
  • CitectSCADA 5.xx, 6.00
Summary:
When connecting to Schneider's OPC Factory Server (OFS) the Citect OPC Client driver returns the error 0x101 - data not yet valid. The topic/device name in OFS is "PLC_501", while the tag is "Sequence_Interlock". The Citect Variable Tag Address is: PLC_501!Sequence_Interlock

Other 3rd Party OPC Clients successfully read and write to OFS. How do I fix this problem? 

Solution:
The OPC Client driver error 0x101 means that OFS does not recognise the Tag the Citect OPC driver is requesting. This is caused by the "!" character in the Variable Tag Address, since this indicates that either an Array index is to follow, or OPC Qaulity flag, or OPC Timetstamp flag.Therefore Citect's OPC Client driver ignores everything after the "!" character, and requests the tag "PLC_501" from OFS. This can easily be fixed through the use of OPC Access paths. To do so, set the following in the Citect.ini file:

[OPCAccessPaths]
IOServerP.IODev_501=PLC_501
(should have the format: <IOServer Name>.<IODevice Name>=<Topic/Device Name>)

Then the Citect Variable Tag Address will be: Sequence_Interlock 
 
Keywords:
data not yet valid, 0x101, OFS, OPC, OPCAccessPaths  

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