Retrieving data from PLC registry

Hi, I am trying to retrieve numerical data from a GEF PLC series 90-30 regsitry, specifically the anlog input %AI0018, using VB6 and the MSComm control but have not ahd any success. The program needs to retrieve data about every 0.1 to 0.5 secs and will dsiplay value in a simple textbox. Could anyone give an example of what theyd code to achieve this.

Thanks

http://support.microsoft.com/support.../Q140/5/25.asp