Talk:Wired logic connection

What function represents wired logic - AND or OR?

What is wired-OR logic? How do we realise this logic? Does the active level of the connected signals make the difference?

They are both wired logic depending on how the diodes are wired and where a resistor, if any, is placed. With a wired-AND, the levels would matter. A wired-OR is when you put 2 cathodes of diodes together. If a signal goes through either line, you get a high signal on the output. The diodes isolate the signals from 2 or more lines so it can't pass to the other line and go up the bus. This is often used for other uses such as voltage isolation such as in a USB device that is externally powered. Thus the USB cannot send voltage to the batteries or external adaptor and the external source cannot feed the USB port or compete with it. A resistor often isn't required.68.67.254.133 (talk) 03:41, 11 December 2019 (UTC)

Wired OR not described correctly

No diodes are needed in wired or using tristate logic. See http://www.ni.com/product-documentation/3544/en/ --agr (talk) 00:00, 25 April 2019 (UTC)

However, if you use an IC, that is not a "wired-OR," since that is not a "passive component."68.67.254.133 (talk) 03:45, 11 December 2019 (UTC)

No diodes are needed. Though specifically not tri-state but rather open collector (and its variants open drain, open emitter, open source). I'm going to rewrite these examples using open-collector outputs only, and will simply point to the diode logic page to show how to do it using diodes. Em3rgent0rdr (talk) 19:21, 18 January 2023 (UTC)

(edit) I'm considering using the symbol for open-collector buffer: https://www.ti.com/lit/ds/symlink/sn7407.pdf Em3rgent0rdr (talk) 19:41, 18 January 2023 (UTC)

I made an svg version of the official symbol for open collector or open drain output. I'm going to use that for the circuits.

Open-collector or open-drain buffer

Em3rgent0rdr (talk) 22:51, 18 January 2023 (UTC)

This schematic is hard to understand and doesn't explain the concept at all well. Bring back the diode form. It was less confusing and didn't require us to master arcane ANSI schematic symbols. --Wtshymanski (talk) 00:43, 18 September 2024 (UTC)

Wired logic can be done with diodes and it can be with the different "open" outputs and this article has examples for both types (the section "Compatibility of wired AND OR using diodes" has animated diode AND and OR gates). Would you prefer to first explain the diode examples and then later explain the open output versions? It might be be a little redundant cause this article already links to the sections in Diode logic describing how the diode gates work. I'm open to whatever makes this article clear, but we can't leave out the "open" output versions because that would make this article incomplete.

The ANSI symbols anyway are useful, because they can describe either BJTs or MOSFETs and the symbol can be at the output of any logic gate or IC, and if needed, each symbol could be explained in a short parenthesis, like "(⎐ is either LOW or OPEN)" and "(⎏ is either HIGH or OPEN)".

(The first comment's ni.com link describing wired-or from open-collector outputs is dead but is still archived at https://web.archive.org/web/20190825155004/http://www.ni.com/product-documentation/3544/en/) Em3rgent0rdr (talk) 06:30, 18 September 2024 (UTC)

I've been puttering with electronics since the tube radio days and I didn't recognize the ANSI symbol. To the non-annointed, the schematics don't convey any useful information. This article is about "wired logic connections", not ANSI symbols. The diode symbols are simpler to understand and since this isn't a textbook we can wave our arms and say "Similarly, open-collector logic gates can be connected as wired OR or wired AND connections." and maybe explain why one would indulge in such connections and their limitations. --Wtshymanski (talk) 01:07, 21 September 2024 (UTC)