Here’s an example where a desktop computer running Director receives data from a BX-24. In this case, the BX-24 is sending 3 bytes, one for each of 3 analog sensors. the Director program checks to see how many bytes there are in the serial port buffer. If there are none, it asks for data. If there are five, it reads the data into five variables. It runs this checking routine repeatedly (in the exitframe or idle), so that if there are some bytes, but not a full three, it skips the whole routine and goes about its other business.
This example uses Geoff Smith’s SerialXtra version 1.0 for Director.