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

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Quatech QSC-100 user manual