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I have an intercom display, Elvox 5721, and I'd like to program it with its software, called "saveprog".

It has a 6 pin programming connector which requires Elvox's cable which is called 692I/U as in this link.

This cable is hard to get and expensive, but I know for sure that it's an FTDI (according to the drivers of the cable), maybe a UART or other low voltage serial protocol. I think it's not RS232 because I measured only about 1V on a couple of pins. The problem is that I don't know the pinout of this connector in order to prepare one by myself and succeed to connect it with my PC.

Is there a method to extract the pinout only by external tests? I have an osciloscope, DVM, logic analyzer.

Any ideas what should I do to find the pinout? Thanks!

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    \$\begingroup\$ Do you have a scope? Because multimeter averages multiple measurements over time, so 1V on multimeter isn't exactly representative of what's actually on the line. It could be some chatter there, so it averages out to 1V. \$\endgroup\$
    – Ilya
    Mar 11, 2022 at 9:28
  • \$\begingroup\$ Yes, I had for now only a multimeter, I'll have the scope and logic analyzer in a couple of days. \$\endgroup\$
    – Avihai
    Mar 11, 2022 at 9:31

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Looking on the Vimar website, there appears to be a similar device that uses a DB9 connector for RS-232. It seems a reasonable starting point to investigate if the 6921/U is simply USB to TTL level UART.

enter image description here source: https://www.vimar.com/en/int/catalog/product/index/liv/L1400L2715L32299?page=1

Once you have your scope, finding power and ground would be my starting point. Look for stable voltages first.

If the device uses all 6 pins, it could be using this pinout. It's impossible to say for sure, but as previously mentioned, this is where I would start.

enter image description here source: https://www.artekit.eu/doc/guides/ak-rs232-family/

If that was successful, then I would think about proceeding with a logic analyser. BUT FIRST, I would check that the analyser is protected from higher voltages. Some older models of Salae Logic's range do not have over-voltage protection of +/- 25 volts.

If yours does not, investigate how to protect your device. Look at MOVs or Zeners.

enter image description here

source: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019MvVSAU&l=en-GB

It is worth considering however, what would be the impact if you brick the device and it ceases to function?

A final word of warning, please be very careful when probing anything that is connected to 220V mains!

Good luck - let us know how you get on!

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    \$\begingroup\$ Thanks for the answer, I'll update after I perform more tests with the scope. Of course, I don't want to brick the device, but once I measure the voltages I'll think again about the next steps. \$\endgroup\$
    – Avihai
    Mar 11, 2022 at 11:54
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    \$\begingroup\$ raaymaan - Hi, Please remember to include the link to the original webpage (or PDF file) for each resource (in this case, image) copied from elsewhere, in order to comply with this site rule. Thanks. \$\endgroup\$
    – SamGibson
    Mar 11, 2022 at 16:22
  • \$\begingroup\$ Woops. Edited and added references. Thanks. \$\endgroup\$
    – raaymaan
    Mar 21, 2022 at 11:21

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