Dear Velleman Support,
I bought a new PPS10 this week from a dealer here in Germany. Measuring itself works fine. But unfortunately I get no correct measurement on the PC.
Today I did intensive testing to determine if there is a problem with my configuration or the PPS10.
First of all a description of my testing conditions:
- Problem occurs on 2 different computers
- Problem occurs on Windows 7 as well as Windows XP
- Both Desktop PCs I’ve tested with have onboard Com Ports (No USB Adapters used)
- PPS10 powered with alkaline batteries. Unfortunately I don’t have a matching external power supply at the moment
- Firmware of the PPS10 is “May 2006 Build 080506F01” (is there a newer one ?)
- tried to reset the PPS10. Doesn’t change anything.
During all the tests described below a square wave was measured. Here is what the Scope showed on the screen (all the time):
When I start the PC program, I get a reading but the graph is redrawn only every few seconds. It takes between 1s and 14s in a very irregular manner. Data is shown more sporadically than systematically. The settings are recognized correct except of the triggering. The Triggering field on the status bar shows always “norm” instead of “run”.
That few data shown differs between a clean measurement without much jittering and a totally jittering measurement.
Hereby the “clean” measurement has strange values. First I thought the data packages would be send in another order (newest samples first, oldest samples last). But the volt values themselves do not match the Curve on the Display of the scope.
The Pictures below show what the PPS10 Software looks like:
To examine the data arriving from the scope to the PC more detailed I’ve downloaded a Demo Version of a Terminal program: http://www.eltima.com/products/serial-port-monitor/
The data arrives absolutely continuous without any pauses. Here’s an extraction from the measurement:
42 41 0a 01 07 08 06 00 73 72 73 72 73 72 73 72 BA......srsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 72 72 73 72 srsrsrsrsrsrrrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
72 72 72 5f f9 fd f9 fd f9 fd fd fd f9 fd f9 fd rrr_ùýùýùýýýùýùý
fd fd fd fd f9 fd fd fd f9 fd f9 fd f9 fd fd fd ýýýýùýýýùýùýùýýý
fd fd f9 fd fd fd f9 fd fd fd fd fd f9 fd fd fd ýýùýýýùýýýýýùýýý
fd fd f9 fd fd fd f9 fd f9 fd fd fd f9 fd f9 fd ýýùýýýùýùýýýùýùý
fd fd f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd ýýùýùýùýùýùýùýùý
f9 fd fd fd fd fd f9 fd fd fd f9 fd f9 fd f9 fd ùýýýýýùýýýùýùýùý
f9 fd fd fd fd fd fd fd f9 fd fd fd f9 fd f9 fd ùýýýýýýýùýýýùýùý
f9 fd fd fd f9 fd f9 fd f9 fd f9 fd fd fd fd fd ùýýýùýùýùýùýýýýý
f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd fd fd f9 fd ùýùýùýùýùýùýýýùý
f9 fd fd fd f9 fd fd fd f9 fd f9 fd f9 fd f9 fd ùýýýùýýýùýùýùýùý
fd fd fd fd fd fd fd fd f9 fd fd fd fd fd fd fd ýýýýýýýýùýýýýýýý
f9 fd fd fd fd fd fd ff 42 01 0a 01 07 08 06 00 ùýýýýýýÿB.......
73 73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 ssrsrsrsrsrsrsrs
72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 rsrsrsrsrsrsrsrs
72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 rsrsrsrsrsrsrsrs
72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 rsrsrsrsrsrsrsrs
72 73 72 72 73 72 73 73 72 72 72 5f 5f f9 fd fd rsrrsrssrrr__ùýý
fd fd fd f9 fd fd fd fd fd f9 fd f9 fd fd fd f9 ýýýùýýýýýùýùýýýù
fd fd fd fd fd f9 fd f9 fd f9 fd f9 fd fd fd f9 ýýýýýùýùýùýùýýýù
fd f9 fd fd fd fd fd fd fd f9 fd f9 fd f9 fd f9 ýùýýýýýýýùýùýùýù
fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd f9 fd f9 ýùýùýùýýýùýùýùýù
fd f9 fd f9 fd fd fd f9 fd f9 fd f9 fd f9 fd f9 ýùýùýýýùýùýùýùýù
fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd f9 fd fd ýùýùýùýýýùýùýùýý
fd f9 fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd f9 ýùýùýùýùýýýùýùýù
fd fd fd fd fd fd fd f9 fd f9 fd fd fd fd fd fd ýýýýýýýùýùýýýýýý
fd fd fd f9 fd fd fd f9 fd f9 fd f9 fd fd fd f9 ýýýùýýýùýùýùýýýù
fd f9 fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd fd ýùýùýùýùýýýùýùýý
fd f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd ff ýùýùýùýùýùýùýùýÿ
42 01 0a 01 47 08 86 00 73 72 73 72 73 72 73 72 B...G.†.srsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
73 72 73 72 73 72 73 72 73 72 73 72 73 72 73 72 srsrsrsrsrsrsrsr
73 72 73 72 72 73 73 72 73 72 73 72 72 72 73 72 srsrrssrsrsrrrsr
73 72 73 5f f9 fd f9 fd fd fd f9 fd fd fd fd fd srs_ùýùýýýùýýýýý
f9 fd f9 fd f9 fd fd fd fd fd fd fd fd fd f9 fd ùýùýùýýýýýýýýýùý
f9 fd fd fd f9 fd fd fd fd fd f9 fd fd fd f9 fd ùýýýùýýýýýùýýýùý
f9 fd fd fd fd fd f9 fd f9 fd fd fd f9 fd f9 fd ùýýýýýùýùýýýùýùý
fd fd f9 fd fd fd f9 fd fd fd f9 fd f9 fd f9 fd ýýùýýýùýýýùýùýùý
fd fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd fd fd ýýùýùýùýýýùýùýýý
f9 fd f9 fd fd fd f9 fd fd fd f9 fd f9 fd fd fd ùýùýýýùýýýùýùýýý
f9 fd f9 fd f9 fd f9 fd fd fd f9 fd fd fd f9 fd ùýùýùýùýýýùýýýùý
fd fd f9 fd f9 fd f9 fd f9 fd fd fd f9 fd f9 fd ýýùýùýùýùýýýùýùý
fd fd f9 fd fd fd fd fd fd fd f9 fd f9 fd fd fd ýýùýýýýýýýùýùýýý
f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd f9 fd fd fd ùýùýùýùýùýùýùýýý
fd fd f9 fd fd fd fd ff 42 01 0a 01 07 08 06 00 ýýùýýýýÿB.......
I saved the whole measurement (about 100 packages) as a txt File and imported it with Microsoft Excel . With the function “HEXINDEC” I’ve converted all bytes to decimal values. I sorted 2 different data packages (obviously type “BA”) by hand in an extra worksheet an ploted a graph:
Looks exactly like the “clean” and glitchy data on the PC Software. It seems like the “glitchy” signal is what is shown on the scopes display referring to the samples volt values. Just the high values are totally noisy.
Because I wanted to see all the data sent in a graph to see if there is a certain pattern or something I wrote a simple VBA code that extracts all sample data, ignoring the headers and writes it to another excel sheet.
Here is plot from all packages (about 100):
If you watch different time sections you can see how the “glitchy” and the “clean” signals alternate. And there are also samples that are zero.
In your excellent bulletin board I also found a description of the packages headers: http://forum.velleman.eu/viewtopic.php?f=9&t=1186
From over 100 packages in the text file there are only 6 starting with “BA”. I haven’t studied the header architecture in detail but I assume that not only the Samples are damaged but also the headers. This would explain why using the PC Software for the PPS10 new data is shown only every few seconds.
By the way: This post looks like a similar problem: http://forum.velleman.eu/viewtopic.php?f=9&t=2508. Just not to such a large extend as I am experiencing here. Is there any known solution ?
So after all these testing which cost me nearly half a day I came to the conclusion that my PPS10 has to be defect. Because I have the same results with different Hardware and different operating systems I am quite sure that the problem is not due to my configuration.
The only thing I haven’t tried is to use a external power supply instead of batteries. Any Chance this could change something because of higher voltage on the com port ???
As you can imagine I am really disappointed. I need the scope for my diploma thesis but I also want to use it furthermore for hobby purposes after the thesis. Because I study aerospace engineering and not electrical engineering, I have only basic knowledge in electronics. I hadn’t had high expectations to the device (never had a oscilloscope before). Most of the time I just want to measure some square wave pulses that are used on radio controlled vehicles.
But the PC Connection was the main reason I’ve decided for the PPS10. So I don’t have to take a picture of the display each time I want to show someone what I’ve measured and I am able to analyse data with other programs on the PC.
Otherwise I would have chosen the HPS140.
I guess the best thing to do would be to do the few measurements I need most urgent for my thesis and send the device pack to the dealer I’ve bought it just a week ago.
But I wanted to check if I have overlooked something or if there is any simple fix to the problem. Perhaps it’s a firmware problem, so sending it back would change nothing if the dealer’s devices have all the same firmware. In that case sending it directly to you would be better (but slower I guess).
On the other hand it would be good to have a confirmation that the problem lies definitely at the device, so the dealer can’t tell there would be a problem with my PC or something.
So I wanted to check here first.
Thank you very much for your advice in advance,
Chris
