09-06-2012, 03:45 PM
Electronic Industries Association (EIA)
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Electrical Characteristics:
The RS-232-C specifies the signaling rate between the DTE and DCE, and a digital signal is used
on all interchange circuits. The RS-232 standard specifies that logic "1" is to be sent as a voltage in the range -15 to -5 V
and that logic "0" is to sent as a voltage in the range +5 to +15 V. The standard specifies that voltages of at least 3 V in
amplitude will always be recognized correctly at the receiver according to their polarity, so that appreciable attenuation
along the line can be tolerated. The transfer rate is rated > 20 kbps and a distance of < 15m. Greater distance and data
rates are possible with good design, but it is reasonable to assume that these limits apply in practice as well as in theory.
The load impedance of the terminator side of the interface must be between 3000 and 7000 ohms, and not more than
2500pF.
Mechanical Characteristics:
The connector for the RS-232-C is a 25 pin connector with a specific arrangement of wires.
In theory, a 25 wire cable could be used to connect the Data Terminal Equipment (DTE) to the Data Communication
Equipment (DCE). The DTE is a device that is acting as a data source , data sink, or both, e.g. a terminal, peripheral or
computer. The DCE is a device that provides the functions required to establish, maintain,and terminate a data-transmission
connecting, as well as the signal conversion, and coding required for communication between data terminal equipment and
data circuit; e.g. a modem. Table 4, shows the complete summary of the RS-232-C, e.g., descriptor, sponsor, data format,
etc.
