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Physical
layer standards specify:
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Mechanical
characteristics: for example, the physical
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medium
used for communication (copper wire,
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coaxial
cable, optical fibre, ....), types of connectors,
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....
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Electrical
characteristics: for example, voltage levels
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and
timing of voltages (for fibre: optical
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characteristics)
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Functional
characteristics: for example, pin
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assignments
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Procedural
characteristics: sequence of events for
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transmitting
data based on functional
characteristics
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Example:
RS-232 standard for connecting
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modems
to computers and terminals (latest
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version
is EIA-232-D).
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