That is 2uS after the digit is placed on the line. In 2uS a signal can travel down and back about 590 feet of cable. If a device is sitting on a cable such that it receives the reflected signal as well as the initial signal, it sees two numbers at once. People have told me they have seen DMX512 problems, which were corrected by termination, on cables much shorter than 590 feet. Although I can easily replicate DMX512 problems with cable lengths over 500 feet, I have not been able to duplicate these problems with short cable lengths.
Reflections can occur at both ends of the cable.
Perhaps the delayed signal had been reflected up and down the line several times causing a 2uS delay on shorter cables. A weak signal from the console may aggravate this problem. The problem was not caused by reflections, but by noise or signal distortion. Cable Capacitance and Inductance. In looking at DMX512 signals on the oscilloscope I've noticed signal distortion on relatively short lines.