DdeRequest retrieves data from a server.
ssData is a scalar string with the data.
hConv is the channel number (handle) which is used with other UniPlot DDE functions.
ssTopic is the topic name.
Specifies the maximum length of time, in milliseconds, that UniPlot will wait for a response from the server application in a synchronous transaction. This parameter should be 0xFFFFFFFF for asynchronous transactions. The default value is 5000.