Null Modem Cable Serial Crossover
D-Sub 2.77-Pitch DB9 9-Pin Male to Male
Unbranded 540249A Molded Connector Space Shuttle UL E101344 16-inch
SKU 162922
CB-NM-DB9M-DB9M-xxx
Features:
- Description:
Null Modem Cable Serial Crossover D-Sub 2.77-Pitch DB9 9-Pin Male to
Male Unbranded 540249A Molded Connector Space Shuttle UL E101344
16-inch SKU 162922
- Manufacturer:
Space Shuttle Hi-Tech
- Brand Name or
Distributor: Unbranded
- Model:
(Equivalent & Compatible)
- PN 540249A
- Seller's SKU 162922
- Connector:
- D-Sub DB9 2.77mm Pitch 9-Pin
Male Molded
Connector
- D-Sub DB9 2.77mm Pitch 9-Pin
Male Molded
Connector
- Pinout: (Wiring
Circuits checked with an Ohm Meter, not a Spec, for reference only.)
- A Simple,
Minimum 3-Wire, Null Modem
Crossover Cable (Pin 4 usually is NC, but some devices use it to
detect if the other side is powered on)
- DB9F 1 - NC
- DB9F 2 - DB9M 3
- DB9F 3 - DB9M 2
- DB9F 4 - DB9M 4
- DB9F 5 - DB9M 5
- DB9F 6 - NC
- DB9F 7 - NC
- DB9F 8 - NC
- DB9F 9 - NC
- Shield - Shield
- Marking:
- RU E101344 STYLE 2919 VW-1 80°C 30V
LOW VOLTAGE COMPUTER CABLE SPACE SHUTTLE-C CSA LL80671 AWM IIA/B
80° 150V FT1
- Item Length:
- Overall : 16-Inch
- Wire: 12-Inch
- Weight: 2.8 oz
(estimated shipping weight 6 oz)
- Condition: (Subject
to Availability)
- SKU ______A -
Aged
Open Box, not been used, with signs of cosmetic wear.
- SKU ______N - New
- SKU ______B - Bulk New, seller
repackaged.
- SKU ______E -
Excess
Inventory,
not been used, may have signs of age.
- SKU ______P
-
For parts, Used,
please check your device's manual to
ensure this pinout configuration matches your connectivity needs.
- SKU ______O -
Open Box, unused, may have signs of cosmetic wear.
- SKU ______R - Refurbished to
working condition.
- SKU ______U -
Used,
may have
signs of cosmetic wear.
- Package: Non-retail
packaging, in Unprinted or Reused Box or Plastic Bag.
- For use with or pulled from: (for
reference only)
- Null modem cables are not universally interchangeable, they vary
in how they handle handshaking. Using the wrong type can result
in "digital silence" where devices refuse to communicate because
they don't receive the expected hardware signals.
- Crossover Wiring Null Modem
Cable Pin 2 (Receive) connects to Pin 3(Transmit), specifically
designed to similar devices (DTEs) like two PCs or a PC and a
Printer. These cables are typically restricted to short distance
often with a maximum reliable length of about 25 to 30 feet.
- By how the cable handle
'handshaking' which is the process of devices signaling that
they are ready to send or receive data.
- Simple Null Modem: Only
the transmit, receive, and ground wires are connected. It relies
entirely on software for flow control.
- Loopback Handshaking:
A specific signal wire is jumpered to another pin in the
same connector instead of traveling through the cable to the
other device. It tricks the software making it believe a connection is ready
even without hardware support from the other side.
- Partial Handshaking:
This crosses RTS/CTS control lines while looping others back
locally.
- Full Handshaking: This
crosses all relevant control lines RTS/CTS and DTR/DSR to allow
full hardware flow control, supporting higher transmission
speeds and more robust communication.
- While largely replaced by
Ethernet and USB for consumer data transfer, null modem cables
are still used in several professional fields:
- Administering Headless Devices
- Used to access serial consoles on managed switches, rackmount
servers, and embedded systems.
- Industrial Equipment - Commonly
found in utilities (electric, oil, gas) for monitoring RTUs and
smart sensing devices.
- Kernel Debugging - Software
developers use them to remotely debug operating system kernels
(like Windows via WinDbg or Linux via KGDB) with minimal
overhead.
- Retro Computing - Enthusiasts
use them for file transfers and multiplayer gaming on legacy
systems like the Amiga or older MS-DOS PCs.
- Serial Number(s) Available or
Sold:
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