RS232 Serial Data Collection Resources

The following links are to pages useful to some engineers who design serial circuits. The information and products contained on the links may or may not be useful or correct for your application.

Quick Turn Cables

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C2G (Cables to Go)
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Null Modems

9M/M adapter at Mouser
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9M/F Phoneix Connector adapter at Mouser
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Office Depot, null modem cable
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Jumper Boxes

Jumper box, 25 pin
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Pinout for RS-232 on DB9
While all 9 pins are listed, most applications only use 3 or 5 of these.

Function Name Data Terminal Equipment
Upstream CPU, PLCin/Out
Pin # Data Circuit
Terminating EquipmentDownstreamModems, Peripherals, Dogcatcher Data Logger in/Out
dcd In 1 Out
RxD In 2 Out
TxD Out 3 In
DTR Out 4 In
Ground 5
DSR In 6 Out
RTS Out 7 In
CTS In 8 Out
RI In 9 Out

Here’s a good set of figures for D-sub 9 male and female connectors, as viewed from the pin side (not the cable side).

D-sub 9 MaleD-sub 9 Male
D-sub 9 FemaleD-sub 9 Female

RS-232 Standard
While many companies have taken liberties, an official RS-232 standard does exist. The Telecommunications Industry Association sells it for $147.
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