2
\$\begingroup\$

Background:

I have a device that interfaces with a motor controller over RS-485 via an RJ45 socket. Currently, the port is a standard 4x2 RJ45 connector with the RS-485 using pins 2 and 7.

Eagle Circut

Currently my startup procedure tries to connect to the controller 3 times before notifying the user Device Cannot be found. Check cable.

Problem:

I would like a way to electronically check if the cable is plugged in. By any chance, do 10-pin RJ45 sockets exist where two pins short if a cable is plugged in? If so, what is this feature called? If not, what is a solution used to detect if a cable is present in the system?

\$\endgroup\$
3
  • 2
    \$\begingroup\$ You could short one of the pairs at the motor controller, and then check to see at the other end if there is a short circuit \$\endgroup\$
    – TemeV
    Commented May 31, 2019 at 11:50
  • \$\begingroup\$ Yes, assuming no other solutions, that's the way I plan to go. Only issue is the controller is not easy to modify, so I would need to add a small PCB and use two Ethernet cables. \$\endgroup\$
    – GentlemanS
    Commented May 31, 2019 at 11:53
  • \$\begingroup\$ are both ends of the cable pluggable? ,... if not, then you only need to short two wires in the cable \$\endgroup\$
    – jsotola
    Commented May 31, 2019 at 17:07

1 Answer 1

Reset to default
1
\$\begingroup\$

Depending on the transceivers you have you might be able to go with something like these:

http://www.ti.com/lit/an/slyt257/slyt257.pdf

https://www.renesas.com/eu/en/www/doc/application-note/an1593.pdf

It seems you don't, but if you had full access to modify both sides you could also try something even easier:

https://stackoverflow.com/questions/25232237/is-it-possible-to-know-the-connection-status-of-a-rs232-port

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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