All You Need to Know About Modbus RTU

A Quick Overview of the serial communication protocol Modbus RTU by John S. Rinaldi of Real Time Automation.
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[@beardedsawyer6322]

As an engineer, I think people like this man are desperately needed in the engineering education institutions. He explained it in less than 15 minutes, while universities spend an entire week (if not months) on such a simple matter. Well done, John.

[@skatalite36]

its because universities need to fill up the semester with something and why not to make everything longer? LOL unfortunately true...

[@radhajadon6597]

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[@chiliphil64]

We see he is not a history or geography teacher.

[@d8m3f6h]

@@chiliphil64 He does rock though!

[@Loredo_1]

Dude I deal with a lot of electrical engineers and they're not very smart, they just do math and drawings and they're good at it but when you bring them to real life (the field) and ask them for example: how do you want me to install that motor in there when it's 300 degrees fahrenheit and wire is rated for 90 degrees. Just one of the hundreds of mistakes I've deal with.

[@dushyantbangal169]

Modbus RTU by Mike from Breaking Bad :D Thank you.

[@SitarHero28]

Damn, I was going to make the same comment! LOL.... Very good video.

[@cippollino83]

Dushyant Bangal e

[@ksawery6568]

Jesus, even his voice is similar

[@gerardoserna6889]

@@SitarHero28 xg df8 vd

[@mother_hacker]

🤣🤣🤣🤣

[@henapra]

I cannot believe a video made 11 years ago has one of the best explanations! Thanks John! - From a humble modbus beginner!

[@RealTimeAutomation]

Glad it was helpful!

[@isnainiahmadi1411]

I love hearing an explanation from an expert technician. Simple yet comprehensive.

[@RufusVidS]

Even though I know all this stuff, I find this an awesome presentation! Concise, correct, and accessible! Kudos!

[@RealTimeAutomation]

Glad it was helpful!

[@DodgyBrothersEngineering]

Wow someone who can actually articulate something of interest without beating about the bush. Well done John.

[@patrickduis]

excellent explanation! I'll share it on some forums and linkedin

[@hiteshvijayvargiya4592]

Thnaks John for the video , it helps me understand the Modbus. Easy to understand .

[@renzorisotto7205]

Thank you too..., good speech, a good use of the "Keys", all is clear and presented in a understandable English, especially for those who do not speak as as native speakers !!.

[@RSC2194]

Agree

[@christophermartin1781]

For those of you who are geographically challenged, Lake Baikal is the largest freshwater lake by volume and the deepest lake in the world. Lake Superior is the largest of the Great Lakes of North America.

[@keeganpeters3816]

Haha, I hear that and wondered if he knew what he is talking about in terms of the RTU stuff.

[@parko1965]

I learned more about lakes than I did Modbus

[@simonk9472]

Good point, on to the next video lol

[@DodgyBrothersEngineering]

None of it is relevant if you didn't know he was talking about the U.S to start with.

[@daveogle4239]

exactly. I've been there

[@juanbahamonde6777]

I'm watching this on 2021 in Chile, thx for the video

[@konradb2010]

finally sb clearly explained the difference between RS232 and RS485 to me. Thanks!

[@DanielCharry1025]

That was fast, and a great explanation. Thanks a bunch!

[@skakke]

Great stuff!

[@RealTimeAutomation]

Thanks!

[@nishyu9101]

the explanation was very efficient! really good!

[@ChristopherMocko]

I'm strait off the bus (just graduated) and this video was great. Thanks a lot guys!

[@asuagar]

The explanation of coils/registers and data representation helped me a lot. Thanks for the vid!

[@colindgrant]

Dang, that was good. I just learned the terms MODBUS and RS-485 last week. Your videos gave me a great framework for how this stuff works. Now I will be able to fill in details effectively as I teach myself how to use it. Thanks!

[@aleemkhunkhunakhan4578]

I loss modbus connection motorola RTU through Rs232 please help

[@SNOW99878]

Man, you are awsom, thanks alot and god bless you.

[@RealTimeAutomation]

Glad it helped

[@ChrizRockster]

This is a great video John. I think it would also help to mention if I may, that RS485 Modbus is a 3-Wire network. A lot of people think Half-Duplex and 2-wires. But its critical to note that you have a Positive, Negative and Reference cable. Its advisable to use 2-twisted-pair cable i.e. Belden 9842 (twisted pair is better at noise cancelling than outer shields anyway). As a last resort you can use 1-twisted pair cable with the drain wire acting as the 3rd REF core. Its important to note that the 3rd core is NOT a ground connection but a direct reference for the Positive and Negative wires on the network. Keeping a nice clean network saves a lot of hassle and head-scratching as without a bench scope to hand, some issues are hard to pinpoint.

[@nathanmatthews8172]

Excellent video for someone new in the field. Thank you.

[@RealTimeAutomation]

Very welcome!

[@santaclaus1291]

...some very straightforward explanation off essentials. Well done.

[@RealTimeAutomation]

Many thanks!

[@TimMattison]

A very accessible intro to/refresher on Modbus. Thanks John!

[@kohweipeng5175]

Right to the point, clear to layman. Well done!

[@javx03]

THANKS YOU SO MUCH FOR A CLEAR EXPLANATION ON RTU MODBUS!!!!!! THAT WAS GREAT!!!

[@kevin00861]

Thanks a lot dear Engineer

[@RealTimeAutomation]

Welcome!

[@zltn_brkl]

awesome and short explanation thank you Sir.

[@RealTimeAutomation]

Thanks and welcome

[@BenjaminMaggi]

Excellent intro to MODBUS RTU, precisely what I needed to know before I start working on this protocol Great work ! zillion thanks !

[@Jarito1903]

no joke, best channel in months. Thanks

[@RealTimeAutomation]

Wow, thanks!

[@sglant]

Thank you very much for this valuable content. I have a potential new job where this technology is being used. So this video was really helpful.

[@mervinburns]

Clear and concise. Excellent. Where others make it seem like witchcraft John just makes it seem so obvious. Keep up the good work. John is simply gifted in conveying information.

[@9999afshin]

Nice

[@antonemilit2178]

Im super serial about understanding Modbus

[@GISED_Link]

Thank you for this great video. More than a simply overview. Really great

[@curtharrington]

Excellent intro into Modbus

[@MikeBoxwell]

Thank you for a really informative, well presented introduction to MODBUS RTU. Well explained.

[@dwightgoad1270]

Very good, understandable, and to the point!👍

[@thefoodstudio2567]

Very Helpful, But Superior is larger than Lake Michigan

[@finhunter]

Lake Baikal is the world's largest freshwater lake in terms of volume. It contains about 5521 cubic miles of water, or approximately 20% of Earth's fresh surface water, all five of the North American Great Lakes combined. The largest lake in the United States is Lake Superior, one of the Great Lakes, located on the United States / Canada border. It is largest in both surface area 31,700 square miles and in volume of water 2904 cubic miles (12,100 cubic kilometers).

[@변건동-n8o]

Really thank you for your awesome video. It's really helpful for me

[@RealTimeAutomation]

Glad we could help

[@paulescalante7986]

love your video bro. coolest teacher ever

[@biobrainshock]

This really helped me with my study material, thank you for the video! Looking forward for more...

[@olenaberezan1409]

Thank you, fast and clear!

[@shahrulazmi6711]

Thank you ! Awesome presentation.

[@pwndownddg]

Nice video! :) but at 8:10 when writing the packet on the board, are u sure about the third one? I don't see address on any other modbus data packets that I find online? According to other sources they exist of only ID, function code, data and CRC? Or Am I wrong?

[@neto136]

Thank you. Your video was very helpful

[@djgoziggaga]

perfect video! greetings from germany

[@RealTimeAutomation]

Thank you very much!

[@adisharr]

Thanks John, very well presented and very helpful :)

[@nothingmuchyou]

cool vid :0) thanks for the help. Skip to 7:36 for ModBus RTU packet structure.

[@54m0h7]

Nice video. At my company we have a product that uses an EBM fan which we control over modbus. Just out of curiosity, how would you suggest controlling them? Each one has several parameter, like speed, which need to be set. We are currently using a programmable control by Carel, but we have had issues when we go more than 12 fans on a single controller.

[@saad83]

Thank you very much for the informative video. I am newbie in understanding the network protocols. Is it possible for you to make some video on similarities between Bacnet and Modbus in general? and How can we use gateway to communicate data between Bacnet and Modbus devices? any pointers to such material will be highly appreciated. again thanks a million, saad

[@MrNaranjito1982]

Thank you very much for the video. It helps me a lot!!

[@MitulShah2201]

Thank you very much

[@mokhtarbadraoui4332]

Thank you 👍

[@Everusso-BR]

Thats was really good. Congratulations.

[@PasanKarunanayake]

Thank you John.

[@musicriven]

answered my question in the first 5 minutes, thanks!

[@sharishsss]

You’re a savior!

[@phyowintsoe]

Thanks a lot for this explanation. Watching your series of videos, you have explained about modbus rtu and modbus tcp. Can you also explain about modbus ascii? Is it same as modbus rtu? I m still confusing among those things.

[@ronpearson1912]

So when you say "reprogram everything" what does that mean? How do you program Modbus RTU since modbus is not a programming language. Is modbus embedded into the code that the master device is using?

[@michaelberkemer1796]

Very well done, thank you! Just a little thing off topic - I am inclined to differ on your statement about "the biggest lake in the world". Please correct me if I am in the wrong and see this ranking list here: en.wikipedia.org/wiki/List_of_lakes_by_area Thanks again.

[@1959FlashGordon]

Great job, John. Very helpful. I am confused on one little point. I thought Superior was the largest fresh water lake. :)

[@nikhilkamble3969]

How can we read date and time of Peak demand in EM7230 over modbus ?

[@internetmovieguy]

Does anyone else hear the beeping?

[@riskizoldyck8063]

Hello Sir I have final project about modbus rtu, i want connect HMI with arduino , arduino be a slave, and i want to send string data from hmi to arduino, i use ttl to rs485 converters to connect them , but i still not understand about the address, i try to connect it, but it's not work, can u help me please?

[@ranjit3o]

Thank you John...

[@tabarin]

Fantastic video, so much better than TI's vid and entertaining too

[@RukshanVidurangaPerera]

Thanks... better if you could increase the sound quality a bit.

[@astral_md]

Well done ! Thank you.

[@paradiseworld5389]

thanks alot to explain all of this

[@RealTimeAutomation]

@JUANBET1UK Sorry for the Delay Juan, Modscan would be a great a free download tool to get. It acts as a master on your PC. Just Google Modscan you cant miss it.

[@robertwalker7693]

Thanks John

[@peterfeldman777]

love it. keep up the good work

[@VPStart]

Useful video

[@RealTimeAutomation]

Glad you think so!

[@curiouscavin]

thank you, gr8 video

[@dadush4]

I'm using Python in order to control a motor via modbus, is there any way to change the turn around time without ramping up the baud rate because that would be quite helpful to avoid missing data

[@mikegroger6708]

Great!!

[@sunhao2005]

Hi, John, I want to do a Modbus RTU master software in VB.NET, but I'm a beginner, I don't know how to implement this. Could you give me some tips or procedure of implementing this application?

[@sunhao2005]

Does it contain MODBUS protocol in the VB code? If it is, that's exactly want I want. I‘ll appropriate it if you could send it to me. My e-mail: [e-mail] Thx in advance.

[@zaidakhras1488]

+Sunh Hao if you have it , could you send it to me . My email : [e-mail]

[@RR42636]

+Sunh Hao Hi, I may have what you are looking for. Please send a test email to [e-mail]

[@mahmoudsepehri2666]

What is TRL/2 protocol that SAAB, TANK EMERSON are used?

[@AllanKobelansky]

Lake Michigan is the largest fresh water lake in the world ... contained in one country. Reference: en.wikipedia.org/wiki/List_of_lakes_by_area. Otherwise, it's number 5. Thanks for the video.

[@ksawery6568]

A slave that doesn't get talked to has to SHUT UP! Very helpful video, thank you!

[@EddiLachmann]

Danke, hat mir geholfen.

[@rapidfiredm]

Can both terminals send at the same time or 1 sends then waits for a reply thx

[@renzorisotto7205]

So, what about modbus TCP? ;)

[@Amr.Aldera]

thank you really helpful

[@mlke4258]

Hi John. I am working on a project for a client where their generator paralleling switchgear is controlled by multiple plcs that communicate with Modbus+.. One of the meters (Powerplex Digital Transducers) became wet and stopped working.. I found a replacement- sent it to Bitronics to be refurbed, installed it and verified it works, but it’s not registering the gensets output voltage correctly.. Instead of 480V it’s displaying 120V.. The generator is making 480V- the transducer needs to have the holding registers edited so it will display the voltage properly.. I have a lot of the hardware to do this such as the SA0085 card, or the Schneider TCMP100 PCMCIA card which are both exclusively used for MB+.. I am having issues communicating with the meter via laptop… Any ideas, suggestions?? I would greatly appreciate it.. Thanks..

[@RealTimeAutomation]

Modbus+ limits vendor support. Schneider is the best option I know of.

[@mlke4258]

I’m very amazed with how much information they openly offer.. It turns out, it was an addressing oversight within the BiView configuration… 👌🏻 Thanks for the reply! 👋

[@DingoHammer]

Superior is the biggest freshwater lake by surface area and Baikal is the biggest freshwater lake by volume.

[@techtalklalitesh]

nice

[@aleemkhunkhunakhan4578]

muscat motorola plc 300. In this has come programming communication issue . Can any guy help on this. We searching a vendor in site KSA tosolve this issue

[@alaachahboune2551]

Rs232 bipoint Rs485 multipoint

[@kiarashkiani8927]

Albert Einstien says when you can not explain some ting simple means you don't know it and this video shows when you know some ting

[@NivagSwerdna]

Hi John.. Thanks for the video. I am trying to reverse engineer a modbus RTU temperature logger so I can publish the output of its 10 NTC sensors.... I have got the following response... 02 03 78 02 25 20 00 00 00 64 00 0C 50 00 FF - 02 25 20 00 00 00 64 00 04 50 00 FF - 02 25 20 00 00.... and worked out that the "0C 50" swapped to "500C" is the temperature... 500C in hex is 20492 and the indicated temperature is 49.2C. It seems that this is encoded in 0.1C increments, +20000 and then the lo byte first and then the hi byte. (Also 4E1F=19999 when -0.1C indicated and 4E23=20003 when +0.3C indicated) Any idea if that is a legitimate coding! It seems to produce the right answer. I am using an old AKO-15772 I got from ebay. Thx.

[@hemanbassi2106]

THANKS it was Good!!

[@Kenneth_H_Olsen]

What voltages does it operate on . Are the coils 24V . Air vent shutters openers . Temprature sensors . Motor on . Are these the 230V/24VAC transformers in the cabinets . Automation . You can use a 3G power cable L1 - N - PE line to trafo P. And 2G load actuator 24V, L1 - N . Some loads need power lines along with signal wires. 4G - L1, N, S1, S2 + emc screen . I guess Modbus files under SELV equipment once below 50V, and dont need PE. The TCP Ethernet has a ground wire along with 4 pairs . F/UTP and usually 5V DC . The boys call it Patch cables . The voltage on the signal and the power to drive the unit, sensor, coil or CPU is determining the cable dimensions and lenght . What is the range and specs of PoW power over internet cables ? TCP : catalog.belden.com/index.cfm?event=pd&p=PF_7919A . 100 meter max cable RTU RS232 : en.wikipedia.org/wiki/RS-232 (VGA cable). 25V RTU RS482 : catalog.belden.com/index.cfm?event=pd&p=PF_3105A. -7V + 12V. 400 meter PoE Rj45 : www.veracityglobal.com/resources/articles-and-white-papers/poe-explained-part-2.aspx 25W / 48V DC = 2 Ampere on three twisted pairs. 1 pair for signal device. 24V. 50 meter

[@filtchev]

Awesome!!!

[@mostlymessingabout]

err. Lake Baikal is bigger than all the USA lakes combined

[@vivekthakur9968]

it's good knowledge

[@MrSidra2009]

awesome

[@nickdrozd]

Archer from Breaking Bad is teaching modbus instead of flipping burgers.