RS-422 Differential Signaling (Renesas ISL8490, Arduino MCU) - The Basics (1/2)

[@LovyDuga]

This video help me alot when i studied line driver output of a incremental rotary encoder. Your experimental demonstration makes easy to understand .

[@robertssmorgasbord]

Glad I could be of help 🙂

[@rohit6020]

Thanks Sir ,for sharing this best video about RS422 .

[@Raju-ut6bj]

One of my friend recommend your video to understand RS422. Your RS422 video series is enough to understand ,write in exam and get good marks.😊

[@robertssmorgasbord]

Thanks for the praise! So, what mark did you get in your exam then?

[@Raju-ut6bj]

@@robertssmorgasbord 78/100 ( Communication in Embedded system); and 4.5/5 in RS422 topic.

[@robertssmorgasbord]

@@Raju-ut6bj Congratulations!

[@magge7910]

Thanks for the great video and explanation. The live demonstration is really helpful.

[@robertssmorgasbord]

I thank you for the praise!

[@copernicofelinis]

For some reason I were expecting you to tell the transmitter "You are terminated" with an Arnold Schwarzenegger accent. Nice intro, BTW.

[@robertssmorgasbord]

Thanks :-) Actually, the Schwarzenegger reference never crossed my mind. But of course it is so obvious. I really should have done hat ;-)

[@Antyelektronika]

Hi, good video.For RS-422 it is possible to "speak" with max 10 slaves?, if yes, how addressing is performed?

[@robertssmorgasbord]

Yes, a single RS-422 line driver / transmitter can drive up to ten receivers. However, there's no "addressing". All receivers receive exactly the same data from a single line driver / transmitter. I'll cover multiple receivers in: "RS-422 Differential Signaling (ISL8490, AdUM121N) - The Details (2/4)" kzbin.info/www/bejne/ZoirfICgd8xkh7M

[@LucaniaRobotics]

Hello Robert, I am a little bit confused... Is there a difference between RS422 seen as communication protocol and electrical interface? Because I am considering an encoder line driver 5V Rs422 and I don't understand what the RS422 means in this case. I think it just means that we have a differential conversion in rs422 differential signal. Is it corrrect?

[@robertssmorgasbord]

RS422 is a physical specification for transmitting/receiving asynchronous serial data (differential signaling, signal levels etc.). RS422 doesn't care about the logical format of the serial data transmitted (e.g. 7 data bits, no parity bits two stop bits - or - 8 data bits, parity bit, one stop bit). You could transfer the same serial data via RS232, RS422, etc.. Hope that clarifies things.

[@LucaniaRobotics]

​@@robertssmorgasbord Sorry just another question, if I have a signal A that can be 0v or 5v, with RS422 I will have for A=5V -> A+=5V and A-=0V and for A=0V -> A+=0V and A-=5V or if A=5V -> A+=2.5V and A-=-2.5V and for A=0V -> A+=0.epsilon V and A-=-0.epsilon. Or they could be both good solution? Thank you.

[@robertssmorgasbord]

@@LucaniaRobotics As far as I can tell your first example (0V/5V) is well within the RS422 specification. However, +/- 0.epsilon V wouldn't work (e.g. +/- 0.9V), because the minimum differential voltage (Vod) under load is +/-2V. +/-1V is in that case the minimum on the signal lines under load.

[@MCT249]

Hi Robert Vod (Voa-Von)is for difference between lines, but it seems that vod under load is not correct. It is defined as +-2 but on the graph it can be 4 volt (5-1). I am a little bit confused could you detail it?

[@robertssmorgasbord]

First, I'm assuming you meant Vod = Voa - Vob (not Von). According toThe RS-422 spec Vod max (!) with no load (!) is ±10V ( kzbin.info/www/bejne/bIq6i4CImpJqerM ), and Vod min (!) with load (!) is ±2V ( kzbin.info/www/bejne/bIq6i4CImpJqerM ). So during operation Vod has to be between ±10V and ±2V. The Vod shown in the graph as an example ( kzbin.info/www/bejne/bIq6i4CImpJqerM ) is ±4V, so within the allowed range. Hope that helps!

[@MCT249]

@@robertssmorgasbord I got the point now. We are looking if Vod is in the range , which is given as +- 10V in spec, or not. Thank you for your reply:)

[@robertssmorgasbord]

@@MCT249 You're welcome 🙂

[@David_11111]

yay

[@robertssmorgasbord]

:-)

[@andymouse]

Interesting to see 20M of cable out perform 15 cm of rubbish Du Pont ! interesting stuff....cheers.

[@robertssmorgasbord]

One of these days I will revisit my laboratory water bath and replace its cable (7 mains AC wires) with something that has 3 mains AC wires and 1 individually shielded twisted pairs (for the One-Wire stuff) ;-)