Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 2.00, 2.01

Question: What will happen if you open the same device twice, while passing a different open mode for each call? 

If you open a device that is already open, the DevOpen() function will not physically open another device - it will return the same device handle as the last open. The mode of the second open call will be ignored. If you want to open the device in another mode, close the device, then reopen it in the new mode.