This property sets and returns the number of characters to receive before the Comm control sets the CommEvent property to comEvReceive and generates the OnComm event.
object.RThreshold [= value]
Setting the RThreshold property to 0 (the default) disables generating the OnComm event when characters are received.
Setting RThreshold to 1, for example, causes the Comm control to generate the OnComm event every time a single character is placed in the receive buffer.