Product specifications

PERIPHERALS
Sharp Electronics Corporation
Section-3: More on RS232
RS232 communications for peripheral devices is usually low-speed communications, which
do not demand the tight specifications required for complex communications.
Cabling considerations - you should use cabling made for RS-232 data communications
using a high quality low capacitance data grade cable. The standard maxim length is 50'
but if data is Async you can increase that distance with a good grade of cable.
The RS-232 signal on a single cable is impossible to screen effectively for noise. By
screening (or shielding) the entire cable you can reduce the influence of outside noise, but
internally generated noise remains a problem. As the baud rate and line length increase,
the effect of capacitance between the different lines introduces serious cross talk (this
especially true on synchronous data - because of the clock lines) until a point is reached
where the data itself is unreadable. Using low capacitance cable and shielding each pair
can reduce Signal Cross talk.
The maxim distance will depend on the speed and noise level around the cable run.
On longer runs a line driver may be required. This is a simple modem used to increase the
maxim distance you can run RS-232 data.
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