Quatech QSC-100 user manual

Data Rate		Maximum Load (pF)
	4%	10%	15%	20%	25%
(kbaud)	trans	trans	trans	trans	trans
	time	time	time	time	time
921.6	N/A	100	300	430	470
460.8	100	430	670	900	1100
230.4	330	900	1100	1630	2000
115.2	800	1570	3300	4300	4800

Note 1: The signal transition time ratio is defined as the percentage of the unit interval or bit time (the inverse of the data rate) that is occupied by the signal transitioning from -3V to +3V. The EIA/TIA-232-E standard defines a maximum signal transition time ratio of 4%; most RS-232 receivers will recognize signal transitions with much larger ratios.

With a 4% signal transition time ratio, EIA/TIA-232-E is limited to a theoretical data rate of 200 kbaud. If maximum signal transition time ratio is extended to 10%, 15%, 20%, or even 25%, the maximum data rate achievable using EIA/TIA-232-E can be increased past 200 kbaud.

Note 2: A typical value for capacitance per foot of standard cable is 50 pF/ft.

Quatech QSC-100 User's Manual 28