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What is RS232 and What is it used for? realpars.com/rs232/

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Today you will learn about RS 485. If you are familiar with RS232, then you may already know a little bit about it.

Just like it’s older brother RS232, RS485 is a form of serial communication. Think of RS485 as the younger, faster brother of RS232.

What made it such an advancement over RS232 was the fact that it could transmit not only a single device to device transmission, but also a communications bus to connect multiple devices at once.

The configuration and specifications of RS 485 make it faster and extend the range of data transmission.

You aren’t limited to fifty feet of cable like with RS 232. The maximum cable length for RS 485 is typically listed as 1200 meters or about 4000 feet.

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Comments

    • Rousbell Juarez
      Rousbell Juarez

      LO MÁS INTERESANTE QUE VI EN LOS VIDEOS DE YOUTUBE

      about 6 days ago
    • RealPars
      RealPars In reply to Rousbell Juarez

      Gracias!

      about 5 days ago
    • Muhammed Ismaeel
      Muhammed Ismaeel

      I'm wondering if the realpars programs that give a distance teaching PLC course with a certificate, I'm from Iraq.

      about 8 days ago
    • RealPars
      RealPars In reply to Muhammed Ismaeel

      We certainly offer the option to purchase our Certification of Completion after completing at least 250 of our video courses. You can find more information about our Certificate through the following link https://bit.ly/2LADnPY

      Let me know if you have any further questions.

      about 6 days ago
    • naveen joseph
      naveen joseph

      thank you

      about 10 days ago
    • RealPars
      RealPars In reply to naveen joseph

      You are very welcome!

      about 9 days ago
    • 공돌TV
      공돌TV

      Wow! This explain is very simple and easy to understand!

      about 13 days ago
    • RealPars
      RealPars In reply to 공돌TV

      Great to hear! Happy learning!

      about 11 days ago
    • Acme Fixer
      Acme Fixer

      This video about RS-485 is limited to the industrial control and it doesn't discuss any of the limitations of RS-485. RS-232 and RS-485 are electrical and mechanical interfaces and do not specify how many devices or what speed the data is sent. The video states there is no standard RS-485 connector but the true RS-485 specifications state the type of connector and the number of pins, and anything that does not conform to the specifications is not RS-485. IIRC the original specifications did *not* use a DB-9 connector. So this video leaves out a lot of information that may be needed for an accurate explanation of the RS-485 interface. Thanks for the limited video.

      about 19 days ago
    • David Moran
      David Moran In reply to Acme Fixer

      You forget that the RS in RS-x is 'Recommended' Standard and there is no connector specification. Additionally you as well as the content provider stated DB 9 what was shown is a DE 9. Unfortunately the content provider did not comment on the most often forgotten ground, 2 wire, as shown, is actually 2 wire plus ground, and the 4 wire systems are actually 4 wire plus ground. On smaller systems as shown, were the equipment shares the same earth connection, although there is more noise, will generally function as intended. When doing camera and control over large areas requiring fiber optic transmission between nodes, this becomes very relevant, I used to design networks that covered entire states, as well as border protection for other countries.

      about 17 days ago
    • Adriano Me
      Adriano Me

      Very helpful, Thank you very much Sir.

      about 20 days ago
    • RealPars
      RealPars In reply to Adriano Me

      Great to hear! You are very welcome.

      about 19 days ago
    • Rupin Chheda
      Rupin Chheda

      The range of the bus is higher and it can support faster speeds because of Differential Signalling. The signal sent across the bus is not referenced to ground, but to each other. The difference in signal levels between the bus wires determines a 1 or a 0. Noise if present pushes both the wires up or down in the same magnitude, thereby maintaining the difference in signal levels. USB is a faster bus partly because of differential signalling.

      about 22 days ago
    • Oat lord
      Oat lord

      Isn't ethernet better at controlling devices than 485? Or is this older tech?

      about 23 days ago
    • David Moran
      David Moran In reply to Oat lord

      ​+Oat lord As far a ease of install, Yes Ethernet would be easier due to the standardized wiring and connectors. However the software on the endpoint devices would be more involved and require additional memory adding to cost. This is one of the things that I worked on with one state DOT, standardizing the wiring scheme as there 64 ways you could wire the ends, but only 1 works properly and most of the others will bring the entire network down. The DOT had camera control, traffic light timing and control to/from the controllers, bridge fire alarm monitoring and alarm contacts on 4 fiber optic cables multiplexing video and data to cover the entire state. There are devices to carry RS485 over Ethernet, but again adding cost.

      about 17 days ago
    • Oat lord
      Oat lord In reply to Oat lord

      +David Moran You're way more knowledgeable than me obviously, but I meant it from an ease of installation and wide industry usage of the ethernet standard and tcpip stack. I was asking a question more than trying to make a statement if that makes sense.

      about 17 days ago
    • David Moran
      David Moran In reply to Oat lord

      The better comes from the software the layer 1 is just the methodology used to transfer. Ethernet uses Manchester Bi-Phase which actually requires more transitions per bit.

      about 17 days ago
    • brencostigan
      brencostigan

      RS-485 is more accurately described as the grown up big brother of RS-422. It’s not fair to compare it directly to RS-232. The reason RS-485 still enjoys massive usage in industrial applications is due to the range of physical layer implementations. As stated in the video it supports multi-drop as opposed to just point-to-point like RS-232. However, it can be used in full or half duplex modes. This means that a station on a RS-485 bus can simultaneously transmit and receive data at the same time.
      RS-485 can be transmitted over both optical and copper physical layers. The optical implementations support dual redundant optical rings which are very robust. Both optical and copper layer repeaters mean that each copper segment can be extended to then support up to 255 node addresses (0 to 254) for the overall network. The actual protocols that run over this RS-485 physical layer are also very lean and efficient in data throughput. Profibus-DP is one example, but please note that Profibus does make a number of changes to the underlying RS-485 physical layer rules (capacitance and inductance limits, etc). Profibus-DP can run up to 12Mbps. Unfortunately, RS-485 is probably the single most misunderstood transmission technique due to a lack of understanding about bus termination requirements and correct screen connections.

      about 24 days ago
    • brencostigan
      brencostigan In reply to brencostigan

      David Moran

      This flexibility and ability to in effect cascade these different physical layers has also contributed to its longevity and success. RS-485 devices can also be used to replace failed stations in older RS-422 architectures with very little difficulty, although the reverse isn’t always possible. However, you can drop an RS-485 master into an existing RS-422 slave network with no problems.

      about 17 days ago
    • David Moran
      David Moran In reply to brencostigan

      Very good, RS 232, in most configurations, is point to point Where RS 422 is point to multi-point and RS 485 is multi point to multi-point. Where I once worked we made counter rotating, self healing, multi-master ring modems capable of translation from 485 to/from 232 to/from 422.

      about 17 days ago
    • Ardent Dfender
      Ardent Dfender

      I find this useful and until earlier today at work I had never heard of RS485, but I’ve heard of and used a RS232 Cable connection. I also maybe think 🤔 something that could of also being elaborated on in the age of where almost all if not many controllers have a Ethernet connection when and where a RS485 cable could be useful? I’m just junior programmer but do O.P.A.C. Engineering - Operation, Process, Automations Control Engineering. Wear many hats in what I’m doing from one week to next. Two weeks ago was on a RO plant water system startup at a plant site. It was SLC PLC with redundant processor chassis and all Ethernet connected to plc network switch with remote I/O’s. To connect directly to the SLC Processor while system was all online had to connect via RS232 on the SLC Card to Primary and Secondary Processor. As the Ethernet port was in use on both cards connected to network. That’s an example I can think of and recent where having my RS232 to USB on laptop Serial cable came in handy and was good to have. Such an example also could of being more in depth explained with the RS485 cable in various situations. However, still excellent video to educate and the more I now know.

      about 27 days ago
    • RealPars
      RealPars In reply to Ardent Dfender

      Thanks for sharing your thoughts with us!

      about 25 days ago
    • Soylent Green
      Soylent Green

      Why not just use ethernet?

      about 27 days ago
    • bachelors of trolling degree, 2013
      bachelors of trolling degree, 2013 In reply to Soylent Green

      Ethernet does support a bus topology and can be setup for redundancy. Trust me. I work with it everyday.

      about 23 days ago
    • brencostigan
      brencostigan In reply to Soylent Green

      Also, low cost Ethernet doesn’t support redundant self healing optical rings. You could splice in an FDDI layer into an Ethernet environment to do something similar but at significant cost.
      So it might be easier to ask “what did the Roman’s ever do for us?.....”
      Having said that it is fair to say that Ethernet is being adopted more and more in Industrial communications but Ethernet redundancy is still difficult to realise in cost effective solutions at present. Fault tolerant Ethernet is out there but the capital investment is much higher.

      about 24 days ago
    • Tim Baggett
      Tim Baggett In reply to Soylent Green

      Low cost Ethernet doesn’t go 4000 feet or support a bus topology. But... search Google for “802.3cg”

      about 24 days ago
    • Mohsin Khan
      Mohsin Khan

      sir can i connect load via RS 485

      about 29 days ago
    • RealPars
      RealPars In reply to Mohsin Khan

      If your device has an RS-485 port on it, you can do that.

      about 28 days ago
    • Rakib Hasan
      Rakib Hasan

      Special thanks real pars

      about 1 month ago
    • RealPars
      RealPars In reply to Rakib Hasan

      You are very welcome, Rakib!

      about 1 month ago
    • THIYAGU D
      THIYAGU D

      Thank you rp

      about 2 months ago
    • RealPars
      RealPars In reply to THIYAGU D

      You are welcome!

      about 2 months ago
    • eddahbi eddahbi
      eddahbi eddahbi

      thanks

      about 2 months ago
    • Nick Contabile
      Nick Contabile

      Thank you for the easy to understand flow of this video. It really helped me understand the standard.

      about 3 months ago
    • RealPars
      RealPars In reply to Nick Contabile

      That is perfect Nick! Happy to hear that.

      about 3 months ago
    • Yahya Jaber
      Yahya Jaber

      So RS485 is a physical connection, and on top of it there is the protocol that makes the nodes communicate and control, like modbus, canbus, SCADA...is this correct?
      Thanks.

      about 3 months ago
    • RealPars
      RealPars In reply to Yahya Jaber

      Yes, RS485 is merely a physical (electrical) connection and as you mentioned, some defined protocols such as Modbus, Profibus and so on using it as one of their physical media to make their nodes communicate within the network. Thanks for your question.

      about 3 months ago
    • Civil Yard
      Civil Yard

      Plz, what's the benefits of RS485 for controlling a servo motor with arduino? ?

      about 3 months ago
    • TheHiphopgems
      TheHiphopgems

      Thanks!

      about 4 months ago
    • RealPars
      RealPars In reply to TheHiphopgems

      You are welcome!

      about 4 months ago
    • hemanth 2a7
      hemanth 2a7

      Nice video thank you

      about 4 months ago
    • RealPars
      RealPars In reply to hemanth 2a7

      You are very welcome!

      about 4 months ago
    • mt
      mt

      Brief and useful information about RS-485. Thank you.

      about 5 months ago
    • RealPars
      RealPars In reply to mt

      Great! You're very welcome.

      about 5 months ago
    • Jashu Vala
      Jashu Vala

      As always superb😇

      about 5 months ago
    • RealPars
      RealPars In reply to Jashu Vala

      Thank you!

      about 5 months ago
    • mohamed enan
      mohamed enan

      can you make a video explaining how to link the vfd with plc to control the speed of a 3 phase induction motor and how to program this process

      about 5 months ago
    • RealPars
      RealPars In reply to mohamed enan

      Hi there, I will pass your request on to our creator team.

      about 5 months ago
    • Prakash M.R
      Prakash M.R

      Nice and simple information

      about 5 months ago
    • RealPars
      RealPars In reply to Prakash M.R

      Happy to hear!

      about 5 months ago
    • ali shaan
      ali shaan

      Please make a video on PID. I watched a lot of videos but did not understand.

      about 5 months ago
    • RealPars
      RealPars In reply to ali shaan

      Hi there, I will pass your request on to our creator team.

      about 5 months ago
    • somnoi77
      somnoi77

      Thank you

      about 6 months ago
    • RealPars
      RealPars In reply to somnoi77

      You're welcome!

      about 6 months ago
    • kadirolie23
      kadirolie23

      This is good technologic engineering explained but where is Distributed Control System for more chemical industry

      about 6 months ago
    • Raj Kiran
      Raj Kiran

      Would you make a video on how to manually tune a pid type temperature controller..please

      about 6 months ago
    • RealPars
      RealPars In reply to Raj Kiran

      Hi there, I will pass your request on to our creator team.

      about 6 months ago
    • Tamil Arasan Tamil
      Tamil Arasan Tamil

      Please explain about memory bits,Data blocks ,functional blocks,sfc in simatic manager...
      Specify how to use them ?
      Thank you

      about 6 months ago
    • Dwight Goad
      Dwight Goad In reply to Tamil Arasan Tamil

      Yes, I've been looking for the same thing.

      about 5 months ago
    • RealPars
      RealPars In reply to Tamil Arasan Tamil

      Hi there, I will pass your request on to our creator team.

      about 6 months ago
    • Gaurav Kumar
      Gaurav Kumar

      Please provide video on how profibus works?

      about 6 months ago
    • RealPars
      RealPars In reply to Gaurav Kumar

      Hi there, I will pass your request on to our creator team.

      about 6 months ago