How popular is that old standby async/sync serial data in new embedded designs? I know there are lots of other technologies coming into play from ethernet to wireless, USB, etc., but what percentage of your new designs are using RS232 or RS485? I still see it on almost every project. If not as an intended interface then at least for debugging. Your comments are appreciated. Scott Validated Software
RS232/485 impromptu survey.
Started by ●September 19, 2005
Reply by ●September 19, 20052005-09-19
Not Really Me wrote:> How popular is that old standby async/sync serial data in new embedded > designs? > I know there are lots of other technologies coming into play from ethernet > to wireless, USB, etc., but what percentage of your new designs are using > RS232 or RS485? > > I still see it on almost every project. If not as an intended interface > then at least for debugging. > > Your comments are appreciated. > > Scott > Validated Software > >Async serial is never going away. The simplicity of it vs. USB or ethernet is not even a topic worth discussing - too obvious. Many, many micros will have only async on board for the foreseeable future. As for RS232, it has disappeared from most computers - but USB to async adapters are around. This might be a good time to ask which ones work and which ones don't. Believe it or not, there are many USB to async adapters that just don't work!
Reply by ●September 19, 20052005-09-19
Not Really Me wrote:> How popular is that old standby async/sync serial data in new embedded > designs? > I know there are lots of other technologies coming into play from ethernet > to wireless, USB, etc., but what percentage of your new designs are using > RS232 or RS485? > > I still see it on almost every project. If not as an intended interface > then at least for debugging. > > Your comments are appreciated. > > Scott > Validated Software > >The group I work with has done about 8 controllers over the last 3 years. These all include RS422 async single and/or multi-drop. None of these controllers are sold individually - they are part of a larger machine. The protocols are all passing strings around. These async interfaces are the primary interfaces to these controllers. I can't imagine spending valuable time futzing with USB or some such modern scheme, when there's work to be done.
Reply by ●September 19, 20052005-09-19
Not Really Me wrote:> How popular is that old standby async/sync serial data in new embedded > designs? > I know there are lots of other technologies coming into play from ethernet > to wireless, USB, etc., but what percentage of your new designs are using > RS232 or RS485? > > I still see it on almost every project. If not as an intended interface > then at least for debugging. > > Your comments are appreciated.When the datarate of my device is sufficiently low, I integrate a serial port, usually selectable between RS232 and RS422. These USB drivers are a pain. Who is going to promise me that in 20 years, any USB device is still functional ? They usually rely on windows drivers and MS comes up with a new concept every couple years. With Serial, and the hardware level translator in place I can be sure that the device is interfaceable in another 20 years. Thanks to TexasInstruments, I found an RS485 driver that does 25MBit over 160m, and another set that does 3MBit over 500m. So even with a medium datarate, my devices can have a serial connection. Yes, a serial to USB is proposed external to the device. Rene -- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
Reply by ●September 19, 20052005-09-19
"Rene Tschaggelar" <none@none.net> wrote in message news:432efee3$0$1161$5402220f@news.sunrise.ch...> Not Really Me wrote: >> How popular is that old standby async/sync serial data in new embedded >> designs? >> I know there are lots of other technologies coming into play from >> ethernet to wireless, USB, etc., but what percentage of your new designs >> are using RS232 or RS485? >> >> I still see it on almost every project. If not as an intended interface >> then at least for debugging. >> >> Your comments are appreciated. > > When the datarate of my device is sufficiently low, I integrate a serial > port, usually selectable between RS232 and RS422. > > These USB drivers are a pain. Who is going to promise me > that in 20 years, any USB device is still functional ? > They usually rely on windows drivers and MS comes up > with a new concept every couple years. With Serial, and the > hardware level translator in place I can be sure that > the device is interfaceable in another 20 years. > > Thanks to TexasInstruments, I found an RS485 driver that does 25MBit over > 160m, and another set that does 3MBit over 500m. So even with a medium > datarate, my devices can have a serial connection. > > Yes, a serial to USB is proposed external to the device. > > Rene > -- > Ing.Buero R.Tschaggelar - http://www.ibrtses.com > & commercial newsgroups - http://www.talkto.netThanks for the comments, please identify the TI driver. scott
Reply by ●September 19, 20052005-09-19
Not Really Me wrote:> How popular is that old standby serial data in new embedded designs?Very popular here! We sell industrial electronic modules that often wind up connected to equipment with serial ports. Using a laptop with a USB port might be nice for doing the setup or for loading a program, but only a small part of it's life is spent doing that. And cheap converters are available for that. -- Gary Peek mailto:mylastname@mycompanyname.com Industrologic, Inc. http://www.industrologic.com Phone: (636) 723-4000 Fax: (636) 724-2288
Reply by ●September 19, 20052005-09-19
Not Really Me wrote:> How popular is that old standby async/sync serial data in new embedded > designs? > I know there are lots of other technologies coming into play from ethernet > to wireless, USB, etc., but what percentage of your new designs are using > RS232 or RS485? > > I still see it on almost every project. If not as an intended interface > then at least for debugging. > > Your comments are appreciated.Let me put it this way: Sales started asking about USB versions of our software. We use serial cables and RS-232, but some newer laptops don't have serial ports. We increased the available ports on the software from 1-4 to 1-8 and included a 3rd-party USB converter cable in the box. Any product we have that talks to another device uses RS-232. ANY product. -- Magnus McElroy Electrical Engineer (EIT) HABIT Research (250) 381-9425
Reply by ●September 19, 20052005-09-19
On Mon, 19 Sep 2005 20:08:31 +0200, Rene Tschaggelar <none@none.net> wrote:>Thanks to TexasInstruments, I found an RS485 driver that does 25MBit >over 160m, and another set that does 3MBit over 500m. So even with a >medium datarate, my devices can have a serial connection.Are these distances and speeds for point to point connections only or are multidrop connections also possible ? Profibus-DP (which is essentially RS-485 with asynch characters) is quite picky at 12 Mbit/s at 100 m. Small series inductances are needed in the main line at each DB-9 T-connector to compensate for the branch capacitance, even if the transceiver is just a few millimeters from the connector in each node. Paul
Reply by ●September 20, 20052005-09-20
On Mon, 19 Sep 2005 11:47:16 -0600, "Not Really Me" <scott@exoXYZtech.com> wrote:>How popular is that old standby async/sync serial data in new embedded >designs? >I know there are lots of other technologies coming into play from ethernet >to wireless, USB, etc., but what percentage of your new designs are using >RS232 or RS485? > >I still see it on almost every project. If not as an intended interface >then at least for debugging. > >Your comments are appreciated.In addition to others' comments, you can bit-bang an RS-232 interface on any microcontroller (I couldn't imagine bit-banging USB even on a processor fast enough to do it), no serial port needed (or no EXTRA one needed if the one(s) you have are dedicated to something else). If you're doing on-board interprocessor communication, you don't even need the voltage/level translation (i.e. no MAX232 chip), though most chips have some sync ports that would do better for on-board comm. Even if it's running on a 32.768kHz clock crystal and a watch battery, you can do something like 300 baud in software (I doubt you could power a USB interface with a watch battery, and certainly not for very long). Even if the controller doesn't have a timer, you can do ugly timing loops and at least transmit easily. Receiving isn't as easy as transmitting, but with a timer interrupt you can do full duplex with no problem, up to some max baud rate depending on processor throughput and clock frequency. The next lower-level interface to the real world would be a pushbuton swich and an LED, using the same port hardware as basic no-flow-control RS232 (one output bit, one input bit), but the data rate for this is a lot slower, and a lot of people haven't even heard of Morse code...>Scott >Validated Software
Reply by ●September 20, 20052005-09-20
Ben Bradley wrote:> In addition to others' comments, you can bit-bang an RS-232 > interface on any microcontroller (I couldn't imagine bit-banging USB > even on a processor fast enough to do it)...Bit-banged USB on an AVR: http://www.avrfreaks.net/index.php?module=FreaksTools&func=viewItem&item_id=459
