Fair enough. Here's a 30,000 ft view. The DUE is collecting data from a series of hall sensors and analog temperature, humidity and pressure sensors, as well as from 7 proximity sensors. Those result in the following variables:

Floats:
extTemp (3 or 4 digits for all Temps, one decimal place)
intTemp
coolTemp
exhTemp
atmPres (5 or 6 digits, one decimal place)
extHum (3 digits, one decimal place)

Ints:
linSpeed (2 or 3 digits)
outFlow (2 or 3 digits)
retFlow (2 or 3 digits)
linRevs (2 or 3 digits)
xAngle (2 or 3 digits)
yAngle (2 or 3 digits)

Booleans
sensor1On
sensor2On
sensor3On
sensor4On
sensor5On
warning1On
warning2On

Data is collected by the DUE every 100 ms and I would like to transmit every 500 ms. Sending a bunch of random separate bytes that I believe represent the total length of the data stream took approximately 50 ms, so it should be doable.

The UNO would need to receive the data, do some minimal calculations and display the results on a TFT.

The code for data collection in the DUE and the display in the UNO is all written, tested and works independently (i.e., I can see all the data collected by the DUE in the Serial Monitor, and it's all correct and properly formatted, and the UNO can do the calculations and precisely drive the TFT displaying arbitrary values assigned to dummy variables).

I don't have code example for the transmission because I don't even know where to start arranging the data. I guess at this point i'm looking for pointers on how to even start thinking about the problem, rather than code correction.

And again, you are dealing with a really dumb coder. I can tell you whether a tumor is malignant or not a mile away, but I can't tell the difference between a float and a double unless I look it up!!!

Thanks again!