I have a scientific instrument that uses a DB9 cable to connect to the standard RS232 port on a computer for communication. I've deconstructed one of the cables as I needed to make another one but I am wondering if this wiring pattern is a standard wiring variation seen with DB9 cables or if it is completely proprietary. I don't want to have to make these cables if I don't have to.

DB9 Wiring Diagram

  • \$\begingroup\$ Questions seeking recommendations for products get closed here. Can I suggest that you reword your question to ask for a solution to the problem rather than a recommendation for a product. \$\endgroup\$
    – RoyC
    Oct 28, 2018 at 8:33
  • 1
    \$\begingroup\$ It's more about identifying this particular pinout than about where to buy it. \$\endgroup\$ Oct 30, 2018 at 8:32

1 Answer 1


That is a standard null modem cable with handshake also known as crossover.

It is used to connect two DCE devices or two DTE devices together.

DCE (data circuit-terminating equipment) .... example: modem
DTE (data terminal equipment) .................... example: computer

enter image description here

TXD - transmit data
RXD - receive data
RTS - request to send   
CTS - clear to send
DTR - data terminal ready
DSR - data set ready
  • 1
    \$\begingroup\$ With both DTR/DSR and CTS/RTS handshake. There are cables without one or the other handshake in the wild. \$\endgroup\$
    – Janka
    Oct 26, 2018 at 22:40
  • \$\begingroup\$ Thank god I don't have to make any more. \$\endgroup\$
    – test
    Oct 26, 2018 at 22:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.