Serial Protocol Analyser


Thread Starter



My name is Steve. I am playing around with some serial data (RS232 / RS485) but having suspected response timing issues. Does anybody know of a freeware or shareware protocol analyser that is available.


[email protected]


Curt Wuollet


Do a google search for freeware and datascope on google. there are several around. If you haven't found one by tomorrow I can mail you one from work.


In the following you refer to "easy com" I cannot get any joy from the two links you quote below, and it seems to have been removed from any sites which used to have it.
can you tell me an active download or purchase link, or even email a shareware copy, please. We are in urgent need of such a program.

"avance-systems" don't have any active sites any more.

Years ago we used a program (DOS) called SCOPE which worked well, and used two serial ports to display on alternate lines BOTH directions of a communicating pair of devices. Something like that for 32 Windows would be even nicer? Any
ideas? I would like to run on a notebook out on site, but my (and most) notebooks only have one serial port (if any), but have USB, and one may need to go thru a USB/serial adaptor to get two serial ports.

Ed Schoell
As I understand it, the problem with Windows and Linux doing this sort of thing is that it's difficult or impossible to know precisely when each character arrives or leaves the port, i.e., due to buffering in the UART or the OS drivers. DOS was much simpler and leaner, and so more capable in this regard than more "advanced" OSes.

There is or was a serial protocol analyzer effort for one of the real-time Linux systems, but when I looked into it it had been abandoned, and wasn't
runnable under the current distributions. Here's a link to Yet Another Serial Analyzer, YASA, with the most recent filestamps in January 2000:


This page links to some DOS analyzers:


I've had some success just grabbing serial streams in any old terminal program, but it comes down to guess work to discern commands, responses, echoes, etc., in the absence of reliable timing information.


Ken Irving <[email protected]>

Curt Wuollet

It depends on the protocol in use. I have used a DOS shareware program caled pal10 or something like that. For the usual enquire reply protos it works well and separates out the streams. I seem to recall that it you bought the package you got a gizmo to do it with one port. At one time I had a box from a company called Frontline that worked well, it wasn't very expensive at the time. Might be worth a Google search I'm not sure why no one has done a Linux version but I do know that the the driver can be spoofed into treating the UART as unbuffered. More likely the difficulty is circumventing the tty discipline or replacing it as it likely buffers the data. It is something I have wanted to do for a while as an exercise. You _would_ have intimate knowledge of all things serial when you were done. With NT and W2K I believe you are out of luck as these simply don't allow direct hardware access. It might be doable for Win3.x and Win9X. If so, its very likely been done and a search of or tucows should turn it up. One reason to use dos is that's all that will run on the notebooks that still had two serial ports :^) I don't know about the USB gambit, it would depend on how complete the control over the serial port is. Since the recent trend is to deprecate serial ports my bet would be on the old stuff. I have an old 386 desktop that I boot from floppy when I need a datascope. (It runs early Linux the rest of the time) I could check on the DOS shareware if you'ld like. The single port angle might work and you can probably boot into DOS from a floppy.


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Mark Blunier

apt-get install snooper

Mark Blunier
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Eric Johnson

Ed, I have a copy of the Easy Com program, in zipped exe format, if you want I can email it to you, it's 1.35MB. Also you might want to try the TAL Breakout program, "": , I have used this one just like you stated, with a two port serial device (the
Edgeport/21 from B&B electronics, "": ) connected to the USB port of a laptop to listen to a PC and a controller talking, it worked great.

So, let me know if you would like me to eamil Easy Com to you.

Eric Johnson
[email protected]
There's a fairly good Win32 datascope available from "": called Listen32 ( ~ $50 ). To see the messages go back and forth and in their correct order with some time-stamps, it works fine. The program does not directly access hardware, it is UART independent. The great thing about that is you can buy a $25 Bafo USB to serial
converter and run it, full-duplex, from a laptop computer that has only one real serial port.

There is also a program call Breakout ( DOS only, from BB Electronic, I think ) and an non-PC based datascope that was, at least, available from HP.

Jay Kirsch

Frank Steward

Hi all,

It's a pitty all the link to avance systems were put on non-active. They had a bunch of good share- and freeware. I'm in particular looking
for their program "Quick Odette".
I know this might not be the right place to ask for, but would by chance anyone have this program stored somewhere.
All links I've found on the internet seems to be dead ends. And believe me, this would help me out a lot.

Thanks in advance for any reply on this matter.

You can E-mail me at [email protected]