RealTerm Spy Mode

Yes it does.

That would be impossible because your program opens a com port. RealTerm cannot open that same com port at the same time. Therefore this only works when RealTerm "attaches" at some point in the driver. In fact, it installs a special driver to do this.

Meindert

Hello.

For this sort of troubleshooting on Windows I use:

Andy

use:

Thanks Andy. They don't do a good job of letting you know the differences between the free version and the multiple paid versions. One thing I notice is that the free version doesn't support anything past WinXP (no Vista or 7) and the paid version don't support 2000!

I'll give it a try.

Rick

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I've always used Portmon for this kind of thing:

Not so. I'm running RealTerm 2.0.0.70 (free version) under Win7 64-bit. Works fine. Check the download page at Sourceforge.

I'm not talking about RealTerm. I'm talking about FreeSerialPortMonitor. It seems to run under Vista 32 bit, but I just got an email saying the "x64" [sic] 64 bit systems are not supported "for sure". He seems to be using "supported" instead of "works" as he says "supported but not tested". I find it a bit odd, they have the free version, but list it separately from the paid versions. I can't find any way to compare features except I suppose it has no more than the "lite" version. The free version is only stated to run under XP,

I saw a failure where the response was abnormal while the message out was as expected. Analyzing the error I can see a character was dropped between the PC and the tester. So either the driver is dropping characters or the tester is dropping them. Now I need to monitor the serial line... another search project.

The display on FSPM is not exactly what I would like, way too much white space, but it does the job. It is also rather slow. I echo all data from the app to a telnet terminal and it streams in real time. FSPM meanwhile keeps scrolling and scrolling for many seconds after the burst is done.

I also tried the Microsoft monitor and it has a poor display. The data is all there, but hard to see what is happening. It is more for debugging the PC internal software than the app or external device.

Rick

Whoops. My bad.

Do you have access to a logic analyzer? A digital 'scope with a long capture buffer would work too, but AFAIK the ones that can "interpret" async serial streams are rather pricey.

Much depends on what you need to see in the serial streams, of course, but I've found a LA very handy for checking issues like the effects of FIFO sizes, how quickly (and whether) a response show up after receiving a particular packet, and so forth.

If you do a lot of serial stuff and can spend a few hundred dollars, I can highly recommend this:

It records the actual (binary) waveform with a timestamp for each transition. Of course you can also tell it baud/parity/stop and it will show you the bytestreams (with timestamps for each byte).

Software for both Linux and Windows. I do all my development on Linux, so that was a nice bonus.

It let me figure out a very tricky problem cause by a bit of customer gear switching baud rate on-the-fly while using Xon/Xoff flow control: they sent an Xoff, changed baud rate, and then sent an Xon.

There are cheaper "dongles" that try to do the same thing, but they use off-the-shelf UARTs to decode the two data streams (rx/tx), so you can't troubleshoot low-level stuff (baud rate drift, stop bits missing, glitches, breaks, etc.).

Thanks Rich,

I have a logic analyzer, but it wasn't where I was. It also is a very old unit, and I mean *old*! It only has a 4k buffer I believe. Still it would have been useful just to see the relative timing of the data in the two directions. The first problem made me think something was getting overlapped. That problem is gone and now I am trying to figure out who is dropping characters. A second serial port monitoring the bad channel should do the trick. If needed, I can rig up the special cable with two monitor serial ports and use RealTerm in monitor mode to show the two directions in an interleaved display.

Rick

When all is said and done, I expect to have a device that can serve as a serial protocol analyzer so I'm not inclined to spend a lot on something like this. Thanks for the tip.

BTW, can you point me to one of the "cheaper" dongles? I didn't find anything on eBay. I'd like to see what is out there.

Rick