Talk:RS-422

Unclear

I can't tell what the protocol specifies after reading this article. The language seems vague. Perhaps this is due to my ignorance, but I don't think that matters. The article is too difficult to understand as is. For example, from RS-232, we see, "The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors." If something like this could be on this page, that would be excellent. Even better would be an overview of the contents of the standard (answering questions like, "What are the electrical characteristics?" and "What are the meaning of signals?", etc.), but that of course would take someone a good deal of time.

--Limited Atonement (talk) 19:50, 7 September 2011 (UTC)

But it says that in the lead paragraph. Its even got an infoobox. --Wtshymanski (talk) 19:54, 7 September 2011 (UTC)

Unclear pt.2

The article seems to be confused. Is the maximum speed 10Mbps under 1.2 meters cable length or 10Mbps under 12 meters cable length? — Preceding unsigned comment added by 185.51.13.8 (talk) 15:42, 1 December 2022 (UTC)

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Checked, AN-214 needed a different date, but I fixed that. rchard2scout (talk) 11:24, 29 March 2018 (UTC)

Incorrect diagram labeling?

I think the diagram in the characteristics section might be mislabeled. I think the axis titles should be swapped. Also, does the scale in the diagram match what is being said in the characteristics section? Basically, is the diagram correct based on what is written or is the written text incorrect or maybe I am just missing something. Thanks! — Preceding unsigned comment added by 69.39.221.62 (talk) 18:50, 29 October 2019 (UTC)

The chart is correct. Or rather the axis labels in the chart shown match the labels in 422. The vertical axis is cable length and the horizontal axis is data rate. The primary differences between the chart shown and 422's chart is that the chart shown has the vertical axis labeled "Cable Length in Meters" while the chart in 422 is labeled "CABLE LENGTH - METERS" (vertical axis). The scale on this axis is the same except that 422 uses k meters and the chart shown is in meters. (i.e. 422 has an axis scale label of 1k and the chart shown has 1,000) 422 also has an axis scale label the top cable length point at 1.2k while the chart shown does not have a scale label at the max cable length. The main reason for the differences in the chart shown and 422's chart is that the chart in 422 is hand drawn and the text for the axis labels can be anything, while the chart shown was created in Excel and I was not able to figure out how to make Excel show the exact same thing. Another example of this, 422's horizontal axis has axis units start at 10k and switch to 10M at the end, I couldn't make excel switch units so I simply used k units throughout the horizontal axis.

I suspect that you are missing something, but I've made many mistakes in the past so I could be the one missing something. Your question is not clear enough so let me ask questions back. Are you familiar with log/log graphs? In the text a point on the chart is described as "10 Mbit/s at 12 m". This is the bottom right point on the graph. 10 Mbit is the horizontal axis and is labeled on the graph shown as 10000 (kbit). The 12 m is the vertical axis and is between the bottom line (10 m) and the next line up (20 m). Is that clear? What exactly seems to be wrong between the text and the chart?

EE JRW (talk) 14:36, 2 November 2019 (UTC)

When?

When was it introduced? 84.226.214.17 (talk) 16:09, 28 November 2019 (UTC)

Looks like the first issue was 1975, with Rev. A in 1978. No idea when it actually got used in equipment, though. --Wtshymanski (talk) 00:54, 30 November 2019 (UTC)

Info box mark space voltages

The info box says:

 Mark (1) 	Negative Voltages
 Space (0) 	Positive voltages  

I don't see how "negative voltages" or "positive voltages" has any sensible meaning with regard to differential voltages. Gwideman (talk) 15:17, 14 May 2020 (UTC)

RS-449 pinout graphic

RS-449 pinout is not part of RS-422 Standard it does not belong here. There is already a reference in the text to RS-449 where it belongs. --R2d21024 (talk) 17:26, 11 July 2021 (UTC)