MeTex DSO utilities

Metex, a Korean company, makes two digital storage oscilloscopes. The same parts are also available branded Tenma, with different labelling on the front of the case. I have the single-channel, 2 MHz version.

The oscilloscope comes with Microsoft Windows software to allow you to use the data on your computer. You can also buy a cable, which I did, because I thought the connector on the oscilloscope would be strange and proprietary. It turned out to be a standard 9-pin serial port, so there was no need to buy the cable after all.

I use Linux, so the Windows software doesn't do me much good. I have therefore written a couple of utilities which convert the produced data files to a more useful format. The most important thing to note is that the instructions are in error - they specify the transfer rate as 9600 bps, but it is in fact 4800 bps, a fact that I discovered only after significant aggravation. Ordinarily I would have checked the baud rate, but since the manual specified it, I foolishly assumed it was correct and did not bother to check.

There are two different types of data which can be sent by the oscilloscope. The first is a sent by pressing the RS232 key, and is data about the current waveform or readings. The second is sent by pressing the print key, and is a graphical screen capture.

The following code is available:

read.c
This is a trivial program to read in the data from the serial port (you can't just use cat, because you have to set the baud rate)
description.txt
This is a description of the data sent in the RS232 data file.
metex2csv
This perl script takes the waveform data from the MeTex output and converts it to a comma-separated value file of time-voltage pairs. This can then be loaded by whatever processing program you want to use.
metex2pbm
This perl script takes the screen dump data and converts it to a .pbm file.

There are some parts of the data files I don't understand. I've emailed MeTex with a request for more information, so if they provide some, I'll update the above. I'll probably update the above even if I don't get more data, just to make it more coherent.


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