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By mohammad2020
I have a device that has a communication port but I do not know which type of connection.
I've measured the voltages on pins , that The following values were obtained :

in your opinion , this is which connection??how can determine type connection ?
in The manufacturer's catalog Been picture following :

Also come in the catalog the following descriptions :

By Valen
While not giving the definitive answer, this document seems to explain more what this device (the short cable I presume) can be connected to. And what the Aquamaster is about. Apparently some sort of industrial watermeter. ... master.pdf

From the text in the pdf and these pictures I guess it is a type of serial connection like RS232. But which pin has what function exactly is impossible to tell. The voltages you measured suggest it is 3.5 volt TTL levels (not negative). But I would not trust that assumption. I would analyse the waveforms comming through the wires with a oscilloscope first. If you can get it working on some of those watermeter devices.

This page explains the difference between RS232 and RS424 a bit. ... 1D005AD0CD

p.s I only searched google for Aquamaster MIL RS232 RS424. If you leave out the keyword "RS424" you get the first linked document.