wildbilly,

It should be possible to send data over 20 feet to your display and have it work, but not using ribbon cable. All the conductors are parallel to each other and divided by insulation. In other words you have a bunch of capacitve coupling between the lines. Also the ribbon cable is likely not shielded so any manner of garbage will be picked up from the nearby environment. I have an absolute encoder (10 lines of TTL data) working over a distance of 50 feet in a high RF environment.

First as stated earlier make sure you have cleaned up the power to the LCD with good bypass capacitors with short lead length. You will need to put the displays in some sort of metal box. Then use a shielded cable with twisted pairs (signal and ground on each pair) between the two units. Then if you are still having problems mess with the pulse widths.

Terry