Null Modem Cable Serial Crossover D-Sub 2.77-Pitch DB25 25-Pin Female to Female Unbranded Molded Connector 10FT SKU 101842

Null Modem Cable Serial Crossover
D-Sub 2.77-Pitch DB25 25-Pin Female to Female
Unbranded Molded Connector 10FT SKU 101842
CB-DB25F-DB25F-xxx

Features:

Description: Null Modem Cable Serial Crossover D-Sub 2.77-Pitch DB25 25-Pin Female to Female Unbranded Molded Connector 10FT SKU 101842
Manufacturer: Not Specified
Brand Name or Distributor: Unbranded
Model: (Equivalent & Compatible)
- Seller's SKU 101842
Connector:
- D-Sub DB25 2.77mm Pitch 25-Pin Female Molded Connector
- D-Sub DB25 2.77mm Pitch 25-Pin Female Molded Connector
Pinout: (Wiring Circuits checked with an Ohm Meter, not a Spec, for reference only.)
- A Full Handshaking Null Modem Cable
  - DB25F 1 - DB25F 1
  - DB25F 2 - DB25F 3
  - DB25F 3 - DB25F 2
  - DB25F 4 - DB25F 5
  - DB25F 5 - DB25F 4
  - DB25F 6 - DB25F 20
  - DB25F 7 - DB25F 7
  - DB25F 8 - DB25F 20
  - DB25F 9 - NC
  - DB25F 10 - NC
  - DB25F 11 - NC
  - DB25F 12 - NC
  - DB25F 13 - NC
  - DB25F 14 - NC
  - DB25F 15 - NC
  - DB25F 16 - NC
  - DB25F 17 - NC
  - DB25F 18 - NC
  - DB25F 19 - NC
  - DB25F 20 - DB25F 6 & 8
  - DB25F 21 - NC
  - DB25F 22 - NC
  - DB25F 23 - NC
  - DB25F 24 - NC
  - DB25F 25 - NC
  - Shield - Shield
Cable Marking:
- N/A
Item Length:
- Overall : 10FT
- Wire: 9.6FT
Weight: 7.8 oz (estimated shipping weight 12 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, Unused Open Box, 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, with 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:
  - SN 0112180 Unused Open Box
  - SN 0112181 Unused Open Box