Applies To:
  • CitectSCADA
  • CitectHMI
Summary:
OPC Clients connecting to the Citect OPC server (Citect.OPC) will not show decimal places for tags which have a raw data type of INT. Due to scaling of the data, in Citect screens etc this would appear with decimal places.

This occurs since Citect defines a tags datatype by it's raw type, even though after scaling, internally it may appear as real / float type data. The OPC client has added the tags as VT_EMPTY meaning to let the OPC server decide what is the data type for this item.
 

Solution:
There are a number of options, not all of which will be available or practical depending on your circumstances.

1. Have the OPC client specify the required data type. Not all OPC clients will support this.

2. Make a memory or disk PLC and use Cicode to move the values to an intermediate tag which is of type REAL. This may become impractical for a large number of tags or where you need to read and write data from the same tags.

3. Where the protocol driver in use supports data coercion then you can change the datatype of the tags in Citect, without changing the address or datatype in the PLC. Not all protocol drivers in Citect support this functionality. An example driver which does is ABCLX.

4. Use Real / Floating point tags in the PLC.
 
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