Understanding connectors

Thread Starter


Joined Aug 19, 2023
Good morning, i bought a videotex, and i have no manuals.
It had a 37 pin d-sub female connector, and i think it's something like a serial port.
Do you know what is it, and how to use it (is it like a rs232, 485, or...)?
i can't find any infos, there are much sites that sell cables and connectors, but apart for some type of balun, i can't find any "standard" application for this connector.
Thank you in advance.


Joined Mar 30, 2015
Welcome to AAC!

As with many connectors, there can be many commercial applications. DIYers are free to use standard connectors for non-standard applications. Wikipedia lists some known applications for that connector family.

D-subminiature - Wikipedia


Joined Sep 24, 2015
A picture paints a - well - clear picture. Can you upload a picture of the connector in question? As for "how to use it" - that depends on the way you want to use it. If it's what I think it is - low current should be no problem. Radio Frequencies (RF), depending on the frequency and power - might be OK, might be a problem. It's the devil in the details.


Joined Mar 19, 2019
You could start by mapping the end connections pin to pin for connectivity to find which pins go where? Straight? Crossover? No connection? Once you have the pin-out, then you can read the standards for their pin-out requirements. Laborious but fruitful. Serial and parallel communications cables typically use DB-9 or DB-25 shell connectors. More likely Video? From WIKI: " DC-37 connectors are commonly used in hospital facilities as an interface between hospital beds and nurse call systems, allowing for the connection and signaling of Nurse Call, Bed Exit, and Cord out including TV entertainment and lighting controls."

Jon Chandler

Joined Jun 12, 2008
Let's bring some reality into this thread....

From an article on videotext on Wikipedia, the description for one type of terminal says:

"A 75/1200 baud modem was fitted as standard (could also run at 300/300 and 1200/1200), and connected to the telephone via an old style round telephone connector. In addition an IEEE interface card could be fitted. On the back of the unit there was a RS-232 and Centronics connections and on the front was the connector for the keyboard."

The connector on the left in the picture is a db-25. This would typically be a serial RS-232 connection.

The db-37 on the right is likely a Centronics/parallel printer port. In the days before PCs, Centronics usually used a 36 pin "Cinch" connector, so a printer port is a good assumption.


Joined Apr 16, 2011
Google RS422 connector 37

Long ago, 37 pin D connector was standard for RS422 communications

Of no use now

That's my best guess, but without knowing the terminal make and having access to the manual, a guess is all I can give.

Stick with the 25 pin connector. It will be much easier to work with