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Serial-to-Ethernet Conversion
Tom Williams, PrincipalAir Networking
[email protected]
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Alternate Title
Serial to Internet Conversion
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Serial Concepts
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Concepts: RS232
PC Serial Port Point-to-point Slow (but thats okay)
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Concepts: DTE Data Terminal Equipment Used to be called
terminals What you type on --- a PC, for example
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Concepts: DCE
Data Communications Equipment Modems, for example
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Concepts: DTE versus DCE Straight-through cabling DTE Transmits
on pin 3, Receives on pin 2 DCE Transmits on 2, Receives on 3 Other
signals (modem controls) are similarly
complementary
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Concepts:Normal serial model
DTE connected to DCE Modem (DCE) connected to another modem
via wire or other link Modem (at other end) connected to the
DTE
at the other end
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Concepts: Null Modems Generally used to connect two DTE
devices
Short (< 50 feet) distances only
Swaps pins 2 and 3 Built to deceive
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Recap
DTE connects to DCE We sometimes need to provide (or
simulate)
modem control signals.
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Internet Concept: Addresses
Named postnuke.oldcolo.com
Numeric 192.160.122.202
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Internet Concept: Sockets Application-specific sub-addresses,
bound
to port numbers Web: port 80 Telnet: port 23 Serial: (reverse
telnet) typically port 4000
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Modes: Terminal Server
Serial Port originates communication
Meteorological Station
Serial to Ethernet Converter
WirelessEthernet Radio
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Modes: Reverse Telnet
IP-based user originates communication
Meteorological Station
Serial to Ethernet Converter
WirelessEthernet Radio
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Modes: Virtual Port PC thinks its addressing COM3
Meteorological Station
Serial to Ethernet Converter
WirelessEthernet Radio
WirelessAccess Point
Virtual Link
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Hardware Examples
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Campbell NL100
Robust Interfaces with CS-IO
port directly DCE port (not so good) Telnet Management
Costly
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Vlinx ESP901 Versatile Inexpensive For Campbell, requires
SC32B adaptor or SC929 cable
DTE port (Good!) Telnet, Ethernet Mgmt ESP902 available for
installations with two dataloggers
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Orinoco EC-S Translates directly to
802.11b for wireless networks where practical.
DCE Port (Not so good) Telnet Management Was discontinued in
2001, then restarted.
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Sources for Serial Equipment
Campbell Scientific www.campbellsci.com
Vlinx: B&B Electronics www.bb-elec.com
EC-S: Proxim www.proxim.com use Google to find vendors for
EC-S
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Questions?
[email protected]
