Monitor RS232 comms with millisecond resolution
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From: Paul Carpenter on 21 Jun 2010 08:41 In article <4c1f3dc4$0$3314$8e6e7893(a)newsreader.ewetel.de>, stefan___(a)broering.de says... > > Anyone know the quickest or easiest way of recording a serial data stream > > and timestamping each byte with a resolution of at least 1ms (preferably > > finer)? I can only find cheap or free programs with less resolution, or > > very expensive solutions, often involving special hardware. > > > > I only need to monitor one port, and I don't need to send any characters > > (actually I'm snooping on an RS485 bus). > > > > I'm prepared to use an old PC with a "real" serial port, run MSDOS, Linux > > or whatever other OS will do the job, use some sort of microprocessor to > > capture the data (preferably one I'm familiar with, such as 8051 family or > > PIC) or anything else so long as it's quick and cheap. I just need to get > > the job done, preferably tomorrow! > > > > If you only want to analyse a serial data stream and if you are sure, > that the bits are correct, you can simply read the data with a PC. > > I don?t think, that you need a microcontroller. > > The simplest way is, you take the B wire (or D-) of the RS485 signal and > connect it via a 1K resistor with the RXD* line of the PC and the GND > line of your RS485 Device with the GND-Line of the PC-Com-Port. This is > electrically not ideal, but should normaly work. But You should not > connect the TXD* line (the one, where you see about -8V) of the PC to > the RS485 bus. > > A better solution of course would be the use of a RS485 tranceiver which > is used only in read-mode, e.g. max485. > > Now take a simple program, e.g. in Turbo-Pascal under DOS or Delphi > under Windows and record the data. > > For a one-cannel solution, i would prefer delphi. For a two-channel > solution, where i need the timing between the two signals, it might be > better in DOS. > > With some experience in serial communication, this should be done in > about half an hour. > > With MSDOS or Windows, you can use every baudrate that is a > factor/divider of 115200. Without changing system timing, MSDOS won't give you 1ms resolution only 1/18.5 Hz. Not sure about all forms of Windows and system clock resolution. > best regards > > Stefan DF9BI > > -- Paul Carpenter | paul(a)pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny <http://www.badweb.org.uk/> For those web sites you hate
From: Grant Edwards on 21 Jun 2010 09:56 On 2010-06-21, D Yuniskis <not.going.to.be(a)seen.com> wrote: >> If possible I'd like it to run at a non-standard baud rate (62,500 >> baud). > > IIRC, a "real PC" will give you problems hitting 62,500. > I think the baud rate clock is fed from too low of a frequency > to give you enough precision to hit "any" baudrate you want > (esp at higher rates, obviously) You're right. A "standard" motherboard UART can't do 62.5K. It can do 57.6K and 115.2K, but nothing in between. -- Grant Edwards grant.b.edwards Yow! I'm ANN LANDERS!! at I can SHOPLIFT!! gmail.com
From: Vladimir Vassilevsky on 21 Jun 2010 10:03 Grant Edwards wrote: > On 2010-06-21, D Yuniskis <not.going.to.be(a)seen.com> wrote: > > >>>If possible I'd like it to run at a non-standard baud rate (62,500 >>>baud). >> >>IIRC, a "real PC" will give you problems hitting 62,500. >>I think the baud rate clock is fed from too low of a frequency >>to give you enough precision to hit "any" baudrate you want >>(esp at higher rates, obviously) > > > You're right. A "standard" motherboard UART can't do 62.5K. It can do > 57.6K and 115.2K, but nothing in between. Load good old DOS, set up PC timer interrupt and do bit banging. You can i/o at the standard LPT port as fast as ~1.5MHz or so. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
From: WangoTango on 21 Jun 2010 11:39 In article <EpmdnWB348YFOIPRnZ2dnUVZ_qGdnZ2d(a)giganews.com>, rowan(a)n_o_s_p_a_m.sylvester-bradley.org says... > Anyone know the quickest or easiest way of recording a serial data stream > and timestamping each byte with a resolution of at least 1ms (preferably > finer)? I can only find cheap or free programs with less resolution, or > very expensive solutions, often involving special hardware. > > I only need to monitor one port, and I don't need to send any characters > (actually I'm snooping on an RS485 bus). > > I'm prepared to use an old PC with a "real" serial port, run MSDOS, Linux > or whatever other OS will do the job, use some sort of microprocessor to > capture the data (preferably one I'm familiar with, such as 8051 family or > PIC) or anything else so long as it's quick and cheap. I just need to get > the job done, preferably tomorrow! > > If possible I'd like it to run at a non-standard baud rate (62,500 baud). > > Thanks - Rowan > I kind of scanned through he replies and I don't think I saw this mentioned. *IF* you don't have much data to dig through, or you have lots of time on your hands, you can use a logic analyzer and get ns resolution if you want. Many of them have settings to mark a channel as a serial input of differing type, UART, I2C, SPI and so on, and then mark the data up appropriately. All you need is access to the logic side of the transceiver, or the logic signals for on board busses. I am only mentioning it because I have used it for a very similar purpose. So, the software the comes with the Digi View from Tech Tools will let you set multiple inputs up as serial data with any baud rate and combo of start and stop bits, parity and so on, and display the massaged data bytes with full timing info available on every level transition, including the start bit. Jim
From: d_s_klein on 21 Jun 2010 12:37
On Jun 20, 4:34 pm, "rowan.bradley" <rowan(a)n_o_s_p_a_m.sylvester- bradley.org> wrote: > Anyone know the quickest or easiest way of recording a serial data stream > and timestamping each byte with a resolution of at least 1ms (preferably > finer)? I can only find cheap or free programs with less resolution, or > very expensive solutions, often involving special hardware. > > I only need to monitor one port, and I don't need to send any characters > (actually I'm snooping on an RS485 bus). > > I'm prepared to use an old PC with a "real" serial port, run MSDOS, Linux > or whatever other OS will do the job, use some sort of microprocessor to > capture the data (preferably one I'm familiar with, such as 8051 family or > PIC) or anything else so long as it's quick and cheap. I just need to get > the job done, preferably tomorrow! > > If possible I'd like it to run at a non-standard baud rate (62,500 baud). > > Thanks - Rowan > > --------------------------------------- > Posted throughhttp://www.EmbeddedRelated.com Have you seen this: <http://www.232analyzer.com/232default.htm> ?? According to their hype, "All monitoring modes available in 232Analyzer software come with timestamps in milliseconds." RK |