What is RS232 and What is it Used for?
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- čas přidán 24. 07. 2024
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Today you will learn about RS232. It is a phrase you may hear fairly regularly in industry, especially by the older guys. Hopefully this video will clear some things up for you.
What exactly is RS232? First and foremost, it is a form of serial data transmission. Or simply put, it is a form of communication. Most people simply called it a serial connection.
What exactly is RS-232? First and foremost, it is a form of serial data transmission. Or simply put, it is a form of communication. Most people simply called it a serial connection.
At one time, it was the most used form of data transmission. You will probably recognize the standard 9 pin DB9 cable. Simply put, RS-232 transmits signals using a positive voltage for a binary 0 and a negative voltage for a binary 1. But what do the PLCs use RS232 for?
PLCs use RS232 to talk to other modules or even other PLCs. These modules can be anything that also uses RS232 such as, an operator interface or HMI, computers, motor controllers or drives, a robot, or some kind of vision system.
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Max cable length of 50 feet was the standard using the cabling that was available when the RC-232 standard was developed back in the 60s. It's better to say that the max cable length is limited to 2500 pF of capacitance. Cable capacitance is determined by the type of cable used. With CAT-6 cable 2500 pF is about 500 ft. In the real world it's possible to reliably run RC-232 over a CAT-6 cable up to 100 feet without any problems.
I maintain a very large network of 232 equipment. It is routine in our network for 232 to be run well over 300ft.
great work RealPars. i just wanna say thank u for the work you guys are doing ❤
Thanks for letting us know about it. Now including RS485, I now know what RS232 cable is and its disadvantages.RealPars is the place to learn automation and not just programing PLCs.
Thank you Renegade Flower!
Learning about this in college. Very helpful! Thank you!
Great to hear that, Daniel! Feel free to reach out to us if you have any questions along the way.
Happy learning!
Omg I ran so many RS-232 cables throughout a building for terminals. Back in the day RS-232 was on a DB25 using full hardware handshake. Also 20ma current loop was used for long hauls. Originally used to replace telegraphy equipment along the railroad. Western union used it for telegrams on Teletype equipment.
Dont be fooled just by DB9 connectors as RS-232 was originally DB-25 (25 pin connectors)
Subscribed...absolutely perfect, straight out information with out all the garbage ya get with 99+% of you tube videos!!
Thank you! Happy to hear that. Happy learning ;)
great work RealPars. i just wanna say thank u for the work you guys are doing
Thank you, Aakash! We appreciate your support - happy learning!
thank you for making this video easy to hear to novices like me
You are very welcome! Thanks for your support!
Your channel is ammmazing man
Thanks a lot!
Best video.
What i like is easy language
Great to hear!
Great video. I have an avr and a tv with rs232 on them and was not sure how or why they would be used. I think in those two instances they are used to upgrade the firmware.
I enjoyed with every video from this channel
Thank you Ahmed. Happy to hear that!
Thanks to all the channels who helped me to to understand RS 232 and rs485
Really clear and understood, thanks so much
You're very welcome Felix! Happy to hear.
RS232 in the real world is full of nasty surprises though. A lot of equipment isn't entirely compliant.
- The correct voltage levels are +-12V, which is great for driving long cables. But it's also difficult (ie, expensive) to generate electrically from the supplies typically available in equipment, so corners are sometimes cut and the voltage reduced. +-5V is so much easier to make, it's just a cheap charge pump, and most equipment is fine with it over short cables. But then you happen to have that one piece of equipment that isn't, or a long cable, and the connection doesn't work - for reasons you won't be able to identify without electrical test equipment.
- USB-to-RS232 adapters often skip out lines like flow control, RI and DCD. Again, to save money, because most equipment doesn't need these lines. So who will notice? Until someone does. So you end up with adapters that seem to work, pass any test, work on most equipment - but then you start on certain devices, and they fail. Worse, those flow control lines only get used under substantial data transfer - so the link may appear to pass every test, you may even be able to use it to configure your device without any problems, giving the impression that all is well and your serial link is fine - then you send a page full of text to print or a long string of g-code commands and they end up corrupted.
- There's no autoconfiguration. You need to get every setting right - bit rate, parity, start and stop bits, byte length, flow control method. A misconfiguration of length or flow control again may appear to work when testing, but then fail when sending the intended data through.
With RS232, you really need to know everything there is about how it works in order to recognise and diagnose problems. There's a reason USB replaced it, and it's not just because USB is faster.
Thank you for your comment! As you point out, even devices which appear to subscribe to the RS-232 standard sometimes really aren't compliant. There are numerous pitfalls, like line loss over long cables, non-standard pinouts, etc., that can make connections between devices harder than it appears it needs to be. Developing skills in solving these problems requires a detailed understanding of the protocols. Those skills come through experience.
Thank you for making this videos. I enjoyed every videos I watched in your channel.
Happy to hear that! Thank you very much for sharing
In my college days I was study lot about that but I could completely understand after your video..
That is an amazing compliment, Ashik! Thanks for sharing.
I’m watching this trying to understand why it takes twice as long to upload software to our A-10’s via rs 232 vs mil std 1553 and this sort of helps it makes sense. So thank you. Also for some reason it behaves differently when you upload it on either standard which is confusing.
Thank you! very helpful :)
Great! You are very welcome.
Very clear and useful. Thank you.
Glad you liked it!
This is a great video.
Keep going :)
This video really helped me out. Thanks so much and make more great videos.
(P.S. i subbed and hit the bell like you asked)
That's an amazing compliment! Many thanks for your support.
Spot on description!
Thank you, Stephen!
Thank you so much for your everyday information.
You are very welcome!
Thanks!
Super... Every video is just awesome. Keep doing
Thanks a lot for your support!
thank you it was quite useful.
Glad to hear that, Mojtaba!
Thank you for share..
You're very welcome! Happy learning.
Beautiful voice, easy language , great video and very helpful i subscribe in your channel thanks a lot
Hi Hakim, thanks a lot for your kind compliment! We are always extremely happy to hear such positive feedback! If you ever have any questions, feel free to reach out to us. Happy learning!
I will tell this to the students tomorrow) thanks so much
Thanks for sharing, Alex!
SIR
Yr video "RS232"
Wached yr above video and I LIKED IT. I find it is useful to know.
Positive features of yr video are:--
1 Excellent video production (technically) and presentation.
2. You spoke in OXFORD ENGLISH , distinct / clear pronounciation and clearly audible.
3. Precise compact information presented to make the viewer understand clearly.
4. Lastly yr summarising what all you explained earlier/ all the while helps memorising key important points.
Vatsa INDIA.
Thanks a lot for your positive feedback! We are happy that you are enjoying our courses! Keep it up, happy learning.
it might have been helpful if they got it right. check my comments to both the poster and brek martin who both got it wrong.
Great channel, great videos, thanks for the efforts, keep it up . Thanks a lot
Thanks a lot, Wiam! Great to hear that.
DB9 Two rows of pins, HD15 (VGA) is three rows of pins, they look alike so much.
Very good explanation
Thank you!
helpful .. thanX
Thank you so much!
You're very welcome!
Is it possible to connect two or more devices in a parallel connection to a single UART channel for both Rx and TX
It is possible, but voltage drop and connection integrity may be issues if not done properly. There are many commercially-available devices available that will allow you to connect multiple devices as you describe.
thank you
Thank you
useful video
well explained thank you! and i also had a laugh with the slow RS232 :)
Glad you liked it, David! Thank you for your support
Thanks. Could you make a video on how to read electronic and electrical diagrams step by step with examples!
Hi Andy!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
like always ، good job
Great to hear! Many thanks!
Good explanation ....thxx
Thank you!
Great show
please whats the app u use to create these videos with this form ?
Thank you! Our animators use Adobe Premiere software.
thank you very much
You are very welcome!
Which software you are using ,for make this type of video,please suggest.
Why would RealPars pin this comment but not answer the question?!
thanks ♥
Good explanation
Thank you!
Keep rocking
Hi realpars
When connecting 3 or more devices together do you use a cable splitter? Will it work if i cut the cable and connect the colors together to make a daisy chain?
The answer is under certain circumstances, this may be viable. RS-232 is a point-to-;point, or 1-to-1 communication protocol and does not inherently have addressing capability. However, some manufacturers have layered a hardware or software solution on top of RS-232 that includes addressing using RS-232. The most common way to do this is to use RS-232 to RS-485 converters to extend the communication beyond the 50-foot limit of RS-232 and to add software that routes the RS-232 commands and responses to/from a specific node;
@@realpars so if i add a rs232 to rs485 converter to each device and daisy chain rs485 side with eachother, it should work?
Thanks a lot for this explanation, but i think that the RS232 is a point to point network, wich you can connect only 2 devices, that's why the RS422 and RS485 came after that and allows the multipoint connection, is that correct ?
and it's the physical support used also in the Serial Modbus and ProfiBus network.
You're very welcome! Yes, this is what we mentioned in the video as well. We are working on a new video for RS485.
RS-232 is peer-to-peer and RS-485 is multidrop. I think the image on the video is causing confusion...
Great 👍
Thank you, Umar!
Very helpful
Glad it helped
Can you please tell me what is the difference between usb to RS-232 converter and Modbus protocol
Modbus is a well-established serial protocol that was developed to make it easy for PLC's to obtain data from up to 254 other devices on the same 16-bit network . USB (Universal Serial Bus) is a lower-level connection between two devices. An RS-232 to USB converter is a piece of hardware that allows older RS-232 devices communicate with newer PC's and laptops via USB (newer computers no longer have serial ports other than USB).
This is good teach
Thank you, Ahmad!
good job you are the best
Thanks a lot, Soulaymane!
Very nice video
Thank you!
Thank you sir
You're very welcome, Gaurav!
Thanks for your great chanal
You are very welcome!
very nice video
Thank you!
I have a question, i have an oscilloscope which uses RS232 for PC communication, but it uses a Ethernet-like cable. How do I connect it to my PC?
Edit: a RJ45 connector
Interfacing devices to a PC depends on a number of factors. First, each manufacturer creates a port that is available for communication and is "pinned out" according to their own standard. The first thing I would do is find the documentation provided by the device manufacturer to see what that pin configuration is and if they provide instructions and/or a cable suitable for connection directly to a PC. This would likely need to be interfaced via a USB port (which is a serial port on the PC). The issue is not so much the connections (RJ45 to USB cables are very common), but rather how can the PC interpret the data from the serial device? This usually requires an application or other instructions from the manufacturer of the device. I would definitely contact them directly with questions about how to interface the device to your PC if their documentation does not already address this question.
nice basic info...
Thank you!
Hi, awesome video , I need some help though.
Can you convert a rs232 to ethernet and the back to rs232 with a adaptor?
And would the a PLC still be able to understand the data and continue to send and receive data?
Thanks
Yes, RS-232 to Ethernet adapters are readily available. It may not be as easy as "plug-and-play" to use the data in a PLC, however. The serial data stream is essentially a character stream that would need to be interpreted based on the characteristics of the device. The converter will need to be configured for characteristics of each device (on the Ethernet side: IP address, etc., and on the serial side: baud rate, stop bits, parity, etc.). Most converters come with driver software that allows the creation of a virtual COM port that supports the setup and configuration of the interface.
@@realpars thanks so much , really great if you to take the time to reply to my question!
In the AV Control Systems Industry RS232 is nearly indispensable.
I have a question that came up to me when watching this video. In minute 4:40, you show something that seems like a "rs 232 Network", but is this possible?
Given that rs232 is a point-to-point serial communication, is it possible to connect to the PC and the VFD if the plc above had only one rs232 communication port? there wouldn't have to be a HUB with several rs232 ports or a switch that regulated the information traffic at the points where the connections crossed?
Also, since the computer, plc and VFD are DTEs, wouldn't there have to be DCEs for the two points to communicate?
Does the network you've designed possibly need more components but for simplication purposes there are omitions?
In my opinion, there has to be a HUB between the PC and the VFD that "splits" the cable going to the PLC, considering that both the VFD and the PC already have DCEs that allow communication between different devices.
Thank you for your videos;
Compliments from Portugal
Hi Daniel,
Thank you for your inquiry. Typically, RS232 is designed to operate between a Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) in a direct, point-to-point wiring configuration. However, if you intend to connect two DTE devices, you can employ a null modem cable. This cable features crossed wiring to facilitate communication between two DTE devices. There are two main types of RS232 cables: Straight RS232 and Null Modem RS232. Additionally, using an RS232 hub is a viable option. RS232 technology dates back to 1962, yet it remains in use today.
For further insights and learning resources, feel free to explore the following links.
www.blackbox.com/en-us en.wikipedia.org/wiki/RS-232 us.rs-online.com/view/search?keyword=rs232%20cable
We hope you find them helpful in your learning journey. Happy learning!
AMAZING
Thanks, Shiva!
I like you guys
Thank you!
thank you very
You are very welcome!
Merci 🙏🏽🙏🏽🙏🏽🙏🏽🔥🇭🇹
thanks
What is the bandwidth of serial cable and why it is not being used in real time scenario now a days between router ?
The bandwidth of RS-232 is approximately 20kBaud. Although this fast enough for much of what we need to do for communication, Ethernet is cheaper, faster, and more reliable than RS232. Ethernet is an advanced type of serial communication which is routable, whereas RS-232 is point to point without special multiplexer hardware.
Nice information hartly tq
Thank you, Rakesh!
@@realpars .sir I complete b.tech ..in electrical and electronic which courese better in my future plzz riplay sir..I dicide to start automation coures
Trying to figure out an 80's router machine and how it get's programs from a modern server.
Wonderfull
Thank you!
Nice
Glad to hear that!
Can we send video data with RS232? or only control signals
You can send whatever data you want over the serial port. Just note that it is much slower then a 10Mbit direct LAN connection.
bro explain lvdt and magnetostrictive sensors
I will pass your request on to our team.
my professor provided us this video and said there will be questions regarding the video in the exam :)
please don't upload any more videos, i am joking keep up
That's really cool! Thanks for sharing that with us, and best of luck on the exam!
Problem with our 90's machine. No files available. Moxa boxes for ethernet file transfer. Trying to figure it out..
Great
Thank you!
Yeah. this is big brain time
What's that db 9 cable
DB9 refers to a D-Shell connector that has 9 pins. These types of connections were very common on PC's prior to about 2000, when USB replaced the DB9 connection for serial devices.
Typically, a serial DB-9 cable has the following pinout:
1) Carrier Detect
2) Receive Data
3) Transmit Data
4) Data Terminal Ready
5) Signal Ground/Common
6) Data Set Ready
7) Request to Send
8) Clear to Send
9) Ring Indicator (not often used)
Can we connect multiple devices using Rs 232 please reply
Not as far as I know. For my understanding RS232 is a point to point connection.... correct me if I'm wrong.
I also found same thing
In some cases, you can use "passive splitters" like as: www.blackbox.com/en-us/store/detail.aspx/6-Port-RS232-DB25-Passive-Splitter/TL074A-R4
Yess point to multipoint it is possible
this is the reason why i start reading comment after few seconds watching the video , rs232 is point to point communication and to let it communicate with multiple points you need an adapter (splitter) , the video is good edited but the content is somehow tricki
sir is there any full form of rs in rs 232???
I am not sure I understand your question fully. "RS" in "RS-232" stands for "Recommended Standard". The full RS-232 standard is now called ANSI TIA-232, which is a published standard that is available for purchase/download.
Serial communication can talk with one device only.
Am I right?
Serial communications can be confined to one device per interface, such as RS-232, can be multi-drop to several devices, such as RS-422, or can be shared among several devices with a "hub" like USB. Technically, Profibus-DP and many other fieldbusses are serial in nature, based on RS-485 or other serial precursors. Industrial fieldbusses are what are called bit-serial communications, which is more advanced and capable than simple serial interfaces like RS-232 and Modbus ASCII.
@@realpars Can't you use Modbus to talk to multiple? Just learning, but....
❤
How is RS232 used for multiple devices?
The short answer is that you cannot use a single RS-232 interface for multiple devices. A single RS-232 port generally has one UART (Universal Asynchronous Receiver/Transmitter) and allows connection to one device. However, using a switching mechanism, some manufacturers have developed RS-232 multiplexers, which enable one RS-232 transceiver to communicate with multiple others. Since RS-232 is a voltage-based protocol, there are additional hardware requirements for multiplexing that guard against pulling the signal voltage to below specification. Multiplexing is outside of the RS-232 specification (RS-232 does not support node addressing), so there may be handshaking issues upon implementation. Using a USB hub with multiple RS-232-to-USB converters has been successfully implemented as well, but often there are port assignment issues or instability of device drivers with this configuration.
in another video, you say rs232 only connects to one device but here you connect multi-device, I'm confused now realpars?!!
I agree it appears confusing. RS-232 is a voltage-based, serial communication protocol. Normally, two devices are connected together with a cable and they can communicate via RS-232. There are RS-232 multiplexers that can allow multiple devices to be connected together, but that was not explicitly demonstrated in the video. It is best to consider RS-232 as a protocol that can communicate between a PLC and a single device.
RS-232 is an example of bus?
RS 232 is a point-to-point connection. An RS 232 cable can only connect one device to one other device. The connections shown in the diagrams are not possible.
As shown, you are correct. The video was simply trying to convey that there are a number of different device types that can be connected via RS-232. Thank you for your comment, and hopefully, this will add a little clarity.
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I'm no authority, but isn't it a RS-232 CABLE and a DB-9 CONNECTOR?
To be 100% correct, yes, the cable carries the signal and data, and the DB-9 connector is the most popular connector used for RS-232 cables. In fact, when I was "growing up" in automation, when I would see a cable with a DB-9 connector, it almost always was an RS-232 comm cable.
50 feet = 1500cm
you completely left out rs232 did NOT start out as a db9 but a db25 just like a parallel connection. not only that, in the beginning they both had female connectors on the back of both pc compatibles and cp/m computers. also 2 computers connected with a crossover or null modem cable can actually be considered a peer to peer network. it may have been slow, but it was much easier than transferring files with floppies by a long shot. if you actually want to learn something then google laplink. if i really want to date myself, i can tell you how i communicated with a mainframe, using a serial modem, a dumb terminal over a straight thru 25 pin serial cable at half duplex. that is why serial is so slow, because it is at half duplex, meaning you could either send or receive data but not do both like a full duplex ethernet connection. do you even know what the anacronym modem stands for? it is modulate demodulate, meaning my modem takes digital information, turns it into an audible tone that gets sent over a phone line, then your modem hears it, turns it back into digital information and sends it to the computer. i always laugh myself silly when children like you try to explain computer history and completely screw it up. next time do your homework.
Hi Richard, We are doing our best! Thank you very much for taking the time and sharing your knowledge with us and the rest of the community here.
Richard Benjamin The type of D connector used was never stated in the video. So what exactly was wrong with the video? It wasn’t about modems or vintage computers. In fact there’s nothing preventing full duplex comms over a standard RS232 serial port, and there never was, and many full duplex implementations exist. It’s just unlikely that any of those are dialup modems.
then it looks like you have no idea what you are talking about. about 75 seconds into the video, they very clearly did use the db9 as an example even though it did not exist until ibm created it specifically for the pc/at. in fact the rs232 standard existed LONG before the personal computer and I know this for a fact because I used a serial modem to communicate with a mainframe over a dumb terminal using a straight thru cable. you say there is full duplex serial, then cite some examples. where is your proof? you say I might be talking about a dial up modem? I come right out and say that very plainly. again, you completely missed something.
All it said was “here’s the standard 9 pin connector you might recognise”, which is true for most viewed. It’s standardised by TIA-574. All I asked was is wrong with the video that you would say a child explained computer history and screwed it up. It’s not calling itself a computer history video. Perhaps you are upset because it wasn’t the plot you expected.
again the video very clearly says 9 pin db9 cable, get your so called facts straight. the video also says it WAS called this and it was referred to as that. how is that NOT computer history? obviously they pulled some nonsense off places like Wikipedia and tried to pass that off as fact. every time you make some unsupported claim, all I do is go back and carefully listen to the video, checking and rechecking it just to find out you are wrong.
Rs-232 does not have multipoint capability.
whoa whoa slow down
thank you