Applies To:
  • CitectSCADA 4.xx, 5.xx
Summary:
The Citect DDE driver normally blocks read requests. How do I stop it blocking requests? 

Solution:
To use the DDE driver normally, you would enter DDEDRV in the "protocol" field in the I/O devices form. Instead, to stop blocking requests, use DDEDRV2 in the "protocol" field. This will reduce the performance of the DDE driver and should not be used if the DDE server is capable of blocking requests. 
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