RS-485 (EIA-485) serial interface pinout

x pins UNKNOWN connector layout
x pins UNKNOWN connector


has no common pinout

EIA-485 (formerly RS-485 or RS485) is an OSI Model physical layer
electrical specification of a two-wire, half-duplex, multipoint serial
connection. The standard specifies a differential form of signalling.
The difference between the wires? voltages is what conveys the data. One
polarity of voltage indicates a logic 1 level, the reverse polarity
indicates logic 0. The difference of potential must be at least 0.2
volts for valid operation, but any applied voltages between +12 V and -7
volts will allow correct operation of the receiver. EIA-485 is better
described as un-balanced
interface, as the balanced normallly implies that the voltages on the
differential wires are balanced with respect to ground or earth
potential (eg +5V and -5V), but EIA-485 is usually +5V and 0V .

EIA-485 only specifies electrical characteristics of the driver and
the receiver. It does not specify or recommend any data protocol. Since
it uses a differential line over twisted pair (like EIA-422), it can
span relatively large distances (up to 4000 feet or just over 1200
metres).
The recommended arrangement of the wires is as a connected series of
point-to-point nodes, a line or bus. Ideally, the two ends of the cable
will have a termination resistor connected across the two wires and two
powered resistors to bias the lines apart when the lines are not being
driven. Without termination resistors, reflections of fast driver edges
can cause multiple data edges that can cause data corruption. The value
of each termination resistor should be equal to the cable impedance
(typically, 120 ohms for twisted pairs).

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