RS-232 - still alive and well - Page 1
Forum section: electronics / general

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 29, 2021, 01:59:10 pm
content: Who else expected a young Chinese girl to not only know what it is but also why it's good to have?

author: DiTBho
author_rank: Super Contributor
timestamp: July 29, 2021, 02:38:38 pm
content: Just looked at the title, yes, I have recently Japanese laptop and found the RS-232 is still alive and well, but that girl on Youtube ...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 29, 2021, 07:05:41 pm
content: Well, I expected her to?She's been around for, let's see, 2015 at least, don't remember how many years before that? Her appearance is unconventional, I suppose you might say, but she's got lots of electronics/programming/hacker/maker experience.I haven't followed her career much, but she's definitely out there doing real projects.Tim

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 29, 2021, 07:33:53 pm
content: Yeah, she sure is showing a lot of boobs, but she's doing real stuff and has become pretty knowledgeable. So, hey, why not.As to RS232, I haven't used that in over 15 years or so.If I ever have to occasionally connect to a machine through RS232, I'll just buy a USB-RS232 adapter. But hey.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2021, 07:40:35 pm
content: I use classic asynchronous serial (UART) a lot but not RS232 signalling unless I have to due to choices made by others. RS232 isn't that robust in the end, so either logic level for simplicity and least part count, or some differential solution like RS422/485 or CAN. The latter can be had at the same complexity (a transceiver chip) as RS232.

author: DiTBho
author_rank: Super Contributor
timestamp: July 29, 2021, 07:58:45 pm
content: My Japanese laptop also adds a Canbus @ 1Mbps port with a funny 4 pins connector.My Japanese graphic calculator has a 3 wires serial-ling, which is actually a true LVTTL serial line @ 115200bps.Will Canbus replace RS232? Who knows

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 30, 2021, 01:06:09 am
content: Quote from: T3sl4co1l on July 29, 2021, 07:05:41 pmI expected her to know what it is, but not to have a device that used it. Most modern devices that have a serial port for configuration use a logic level UART connector or integrate a USB UART chip.Quote from: DiTBho on July 29, 2021, 07:58:45 pmOnly if CAN interfaces become as common on microcontrollers as UARTs are now. I would say there's a better chance of USB OTG replacing UART, but UART has the simplicity that others don't.Other potential alternatives would be I2C and SPI. I2C is a bit more complex with addressing while SPI is the fastest but also the highest pin count. What used to be an advantage over UART was no need for a precise clock, but many microcontrollers nowadays have internal oscillators good enough for UARTs.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 30, 2021, 06:52:09 am
content: Quote from: DiTBho on July 29, 2021, 07:58:45 pmFor general purpose maintenance/debug/low cost device port - no. CAN stays where it is useful, and those maintenance ports partially stay in RS232, partially transfer to logic level serial, and partially transfer to more complex alternatives such as Ethernet, bluetooth, other wireless, or custom ports.

author: DiTBho
author_rank: Super Contributor
timestamp: July 30, 2021, 09:04:47 am
content: Quote from: NiHaoMike on July 30, 2021, 01:06:09 amThere are a lot of Freescale MPUs that come with an embedded CAN, also there are a some good and cheap SPI-CAN chip. So, it seems possible.Quote from: NiHaoMike on July 30, 2021, 01:06:09 amBoth my Japanese PDA and laptop come with I2c and SPI. The laptop also has CAN, "RS232-4W"(1), I2C and SPI; however, I2C and SPI are only used internally(2), there is a little connector under the plastic, you can somehow access it, but you cannot connect a cable longer than 20cm, and that's the point! CAN and RS232 can be used with long cables! Even longer than 1m.(1) "RS232-4W" means { 3.3V, TX, RX, GND }, it's sometimes routed to a RJ12/4pin (usually with routers)(2) there are several SPI channels, one connects the boot flash, that contains u-boot.I2C and I2S are used to connect the touchscreen chip, and the sound chip, but there is a fourth channel not used, routed to a small connector.

author: DiTBho
author_rank: Super Contributor
timestamp: July 30, 2021, 09:08:56 am
content: Quote from: Siwastaja on July 30, 2021, 06:52:09 amWith Linux I haven't yet understood if it's classified as "network" device, or "char" device

author: PKTKS
author_rank: Super Contributor
timestamp: July 30, 2021, 01:46:13 pm
content: Have a half dozen devices still using RS232 and COM portsGot some COB type dongles and still wondering if I will buy one of these multi serial PCI COM port adapters to have full RS232 still ready...Either not having the RS232 signaling levels the protocol is still required by some gizmos..Paul

author: rfclown
author_rank: Frequent Contributor
timestamp: July 30, 2021, 01:54:19 pm
content: I'm working on new designs for military gear and RS232 is still required.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 30, 2021, 03:58:17 pm
content: Quote from: DiTBho on July 30, 2021, 09:08:56 amCAN is pretty specific and can't easily replace "byte stream" devices. CAN is absolutely great for certain tasks which naturally fit with the CAN's ideology - publish structured data with identifiers, no "command"-"reply" interactions - but forcing something like a byte stream through CAN is horrible use of CAN.CAN can not () be used as a byte stream, because a hardware-delimited CAN packet is a structured piece of data with specific fields with specific meanings, all important. All CAN implementations I have seen, including socketcan, Kvaser API and PCAN API (it sucks not to have unified API on Windows), implement such structured data; for example, socketcan exposes a CAN packet as aC struct.In linux, as a network device, you are still limited to reading a CAN packet in a byte array usingread(), but AFAIK you can be sure to get a full packet (sizeof (struct can_frame)) at once, i.e., short count should not happen. Typical pattern isCode:struct can_frame frame;nbytes = read(cansoc, &frame, sizeof(struct can_frame));if(nbytes != sizeof(struct can_frame)){// unsupported failure mode, never seen this happen,// maybe someone can confirm if this is _guaranteed_ to never happen?}Worst part of CAN is that it is ungooglable due to the stupid name choice. What next, how about "is" protocol? "l" would be pretty good as well (that's a lower case L in case you didn't already notice, just for confusion.)

author: peter-h
author_rank: Super Contributor
timestamp: August 01, 2021, 02:57:17 pm
content: RS232, 422, 485 will live on, because- the chip costs peanuts (MAX232 sort of thing)- the software overhead is ~zero (CAN USB ETH are all massive, and complicated for customers to use except in very narrow cases)- anybody can use it, straight awayInterfacing serial comms, and making USB-serial converters, etc, is my day job and has been for 30 years. Much less demand these days, for sure, but that's because things tend to get integrated more, and as companies lose people with real skills (retirement) they install turnkey systems which naturally use closed architectures (for customer entrapment).How much surgery has that girl had done??

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 01, 2021, 04:38:34 pm
content: One thing I find lacking with both USB to serial adapters as well as "proper" UARTs on PCs is the lack of standardized support for 9 bit mode, something most microcontrollers support. That provides a good way to implement out of band framing for data values that are a multiple of 8 bits, for example binary data.Quote from: DiTBho on July 30, 2021, 09:04:47 amAlmost every PC has I2C exposed on an external port, that's part of VGA and DVI/HDMI. It is, however, rather low bitrate. Displayport switched to its own serial protocol to work better with stuff like touchscreens.Quote from: Siwastaja on July 30, 2021, 03:58:17 pmSearching "can bus" seems to work at least on Duck Duck Go. It has been a long time since I last used Google for web searching, I suppose if it's even more garbage than it was back then, it's time to switch to something else.Quote from: peter-h on August 01, 2021, 02:57:17 pmShe identifies as a cyborg ("part robot") so quite a bit. Funny thing is, back when I was in elementary school, I had a hard time finding friends (because I read so much about science and technology) so I wished for a robot to be my friend, a wish that kind of came true. I think her unusual appearance is to try to set herself apart from other models in technology like Xyla Foxlin and Sarah Petkus.

author: nctnico
author_rank: Super Contributor
timestamp: August 01, 2021, 05:09:08 pm
content: Quote from: peter-h on August 01, 2021, 02:57:17 pmYou forget reliability. Last year I did a relatively large project which consists of several sub-units. The communication between them uses RS232. The unit itself has a USB port which identifies/works as a serial port.QuoteWay too much if you ask me

author: james_s
author_rank: Super Contributor
timestamp: August 01, 2021, 05:38:24 pm
content: Quote from: nctnico on August 01, 2021, 05:09:08 pmI have a hard time taking someone seriously that tries that hard to get attention, it's a gimmick IMO, it reeks of desperation and it's distracting. She looks like she'd be working in an adult entertainment venue, not an engineering lab.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 01, 2021, 06:41:54 pm
content: Quote from: nctnico on August 01, 2021, 05:09:08 pmActual RS-232 or just a logic level UART? Those terms are often used interchangeably when RS-232 refers to the +-12V signal levels that operate with a UART at the core.On reliability, it's not really true of half duplex RS-485. Most UARTs don't implement CSMA/CD in hardware so it's up to you to do it in software. It's especially problematic if the system doesn't have real time capability. (Some better USB to RS-485 adapters use a microcontroller instead of a standard USB UART for that reason.)Quote from: james_s on August 01, 2021, 05:38:24 pmI don't think she'll be a particularly great dancer with such a high center of gravity.

author: nctnico
author_rank: Super Contributor
timestamp: August 01, 2021, 08:07:09 pm
content: Quote from: NiHaoMike on August 01, 2021, 06:41:54 pmI mean the +/-12V levels. There shouldn't be much confusion about that though

author: peter-h
author_rank: Super Contributor
timestamp: August 02, 2021, 06:48:27 am
content: Most products which are "boxed" and with RS232, have a swing of at least -5V to +5V. You can get that with a MAX3232, which runs from +3.3V.There may be some which swing -3.3V to +3.3V but I haven't seen that.The 0 to +3.3V or 0 to +5V cases tend to be board-level products e.g. development boards.Indeed, RS232 is "reliable" because there is no chance of DHCP not working or any of the thousand other things which break the more advanced methods. Same for RS422 or RS485 which are equally cheap to implement.

author: Raj
author_rank: Frequent Contributor
timestamp: August 02, 2021, 07:07:56 am
content: I highly doubt that it's the S£xy cyborg that's the brain behind her videos. People have speculated that it's her engineer husband.I just want someone unbiased, to meet her in person and test her knowledge out.Kasyan TV used to have a male voiceover, until it became popular. Now a female voices the channels video.Side note:While typing this, I realized that windows has F-ed up my keyboard settings and when I type "#", or shift 3, it prints "£" symbol.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 02, 2021, 01:37:25 pm
content: Quote from: Raj on August 02, 2021, 07:07:56 amThere is no husband, she's a lesbian. Also, a lot of smart Asians are also very good looking. (Look up Kitty Yeung and Xyla Foxlin for more examples in engineering.)

author: DiTBho
author_rank: Super Contributor
timestamp: August 02, 2021, 03:28:07 pm
content: Found a couple of sonar sensors. They offer RS422 as communication link.Nice. I can wire a 5m cable without any problem

author: PKTKS
author_rank: Super Contributor
timestamp: August 02, 2021, 03:38:03 pm
content: Quote from: peter-h on August 02, 2021, 06:48:27 amIndustry grade products are RS232 and GPIB ready ..and LXI counts as a feature...No serious industry device lacks RS232 as of today..https://www.kikusui.co.jp/en/product/selection.php?Category=DC%20Power%20SuppliesIt may vanish someday.. but not now..Paul

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2021, 08:54:33 am
content: You won't find RS232 on most modern test gear. USB and ethernet are standard nowadays (where USB typically mimics a serial port even if it is called USB TMC).

author: PKTKS
author_rank: Super Contributor
timestamp: August 03, 2021, 10:01:27 am
content: Quote from: nctnico on August 03, 2021, 08:54:33 amWell I have placed a proper URL reference for that reason...Depending on the "level" we a are talking... ..serious industry grade devices can not suppress RS232 (yet)and.. I just REFUSE to GROUND my bench test gear with these USB dongles wide spread among everything...I know WINTEL invested insane amounts of money to have the property of USB and HDMI dongles.. and chips and specs.. and they will not let go to the bitter end..But is just pathetic that dongle thing.I have now a bunch of DONGLE for THE DONGLES and new DONGLE version.They are piling up against each other..nahhh I will not ground my bench devices that way...Paul

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2021, 10:10:43 am
content: RS232 is ground referenced just like USB so that doesn't make any difference. RS232 is also relatively slow compared to USB.

author: PKTKS
author_rank: Super Contributor
timestamp: August 03, 2021, 10:29:21 am
content: Quote from: nctnico on August 03, 2021, 10:10:43 amThey are quite different...RS232 has no HUB and when made for "industry grade" device attach...they are safer.They were already made for that... industry COM ports.Not USB.USB a gadget gizmo device.Paul

author: DiTBho
author_rank: Super Contributor
timestamp: August 03, 2021, 11:26:48 am
content: The first time I used a serial, the chip was referenced as "ACIA" and there was an external baudrate generator because the chip was unable to generate its own baud clock. The maximal value was 9600bps, it was the time of BBS and early internet through a serial dial-up modem coupled with a phone, but the common bit per second was 1200, sometimes 2400.In the 1990s, 9600 bps was considered "turbo"Years later, ADSL-modems were able to go up to 115200bps. USRobotics was one of the first modem able to reach 1Mbps, even if the ADSL part of the modem was unable to follow the signal on the phone line with a decent fail rate, and what's the sense of going faster if more than half of the bits are wrong?!?

author: DiTBho
author_rank: Super Contributor
timestamp: August 03, 2021, 11:40:31 am
content: Quote from: PKTKS on August 03, 2021, 10:29:21 amdon't mention it ... USB3-things are really shocking with certain SoC chips.With H3 SoC (2016) you have "combined HDCs", with three controllers OHCI, EHCI, XHCI all multiplexed to the same physical pins, so you also have to program the PHY (and this also implies a bus to communicate with the PHY).OHCI does not even work good, so why is there?!? And with EHCI and XHCI you also have to specify if the PHY and the HDC are set to operate ashostdeviceOTG (<------ this needs an extra pin in the PHY to select{host, device} on demand)gadget (<------ this USB3's stuff, and it's used as a wild way to encapsulate Ethernet over usb)While my old Ath5 SoC (2005) has a simpler USB HDC that only operates as host, and it only supports EHCI, and the PHY is directly connected to the HDC.

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2021, 11:50:42 am
content: Quote from: PKTKS on August 03, 2021, 10:29:21 amDoesn't matter. Besides that equipment should be grounded through the mains ground or an external ground strap bolted onto the device. Not through a detachable interface whether it is RS232 or USB.

author: PKTKS
author_rank: Super Contributor
timestamp: August 03, 2021, 01:12:02 pm
content: I do not ground my instruments (EARTH ground).ALL MY BENCH IS ISOLATED USING DEDICATED TRAFOS.That includes my computer bench (workstations and NAS)One thing is connect 2 devices - PC and instrument - via RS232.Another thing .. is connecting a plethora of small USB gizmos and HUBs..and each using a different set of interfaces and power requirements..Having USB on my bench is a nightmare..I have crafted an ISOLATED HUB just to host these most important ones...Still I am not ok when putting them.. even being ISOLATED (isolated powered HUB)They put a COMMON GROUND among devices..Hard to predict safelyPaul

author: DiTBho
author_rank: Super Contributor
timestamp: August 03, 2021, 01:31:30 pm
content: The perfect isolated UART is ... IrDA, or the optical link used in some multimeters.

author: PKTKS
author_rank: Super Contributor
timestamp: August 03, 2021, 01:36:28 pm
content: Quote from: DiTBho on August 03, 2021, 01:31:30 pmFro DMMs is ok when they have both usually I got them bothFor my Uni_Ts :UNIT-UT-D02 RS232UNIT-UT-D04 USBBut USB SCOPES gizmos and func.gens and other stuff ...hardly will have opto isolated ready cables..My BENCH IS FULLY ISOLATED SETUP - nothing connects EARTH.EARTH connection was banned decades agoDMMs are floating devices.. but grounding USB gizmos adhoc is a hazardPaul

author: DiTBho
author_rank: Super Contributor
timestamp: August 03, 2021, 02:36:34 pm
content: and what about Ethernet connection with isolated transformers?RIGOL sells DSO and function generators with Ethernet. Not expensive, and it offers good bandwidth.