DVM1200 multimeter and Windows 10

hmm indeed that’s a problem.
Could you open in realterm window 1 COM2, disable the echo checkmark and in the other realterm window COM9.
now place your cursor on one of the black windows (where you normally see the incoming data) and click there. Now start typing random things with your keyboard.
You won’t see what you type but the other realterm window should show it. Another method is to go to the “Send” tab and type some random characters in the top input field, then press “Send ASCII”. Now it should also appear the the other realterm window. If not perhaps your com0com configuration is not working.

Screenshot of my com0com settings: we.tl/7zpZLy1ol4 (They are all default btw)

Sorry :wink: but this works fine : If I play a sonata of Choppin on my Keyboard threw the first window, a burst of hexa numbers scrolls on the second. But contrary to what I see on your screenshot, my device manager doesn’t mention any COM port except COM1 that is permanently connected to my 12 years old weather station fitted with a RS232 link: https://we.tl/WdM3uZfQpV

Strange, isn’t it?

No it is not that strange. The com ports of com0com are listed under another category called “com0com - serial port emulators”. I see it in your screenshot too.

But this means the com0com ports work, so the port echo function of Realterm doesn’t seem to work on your computer. Could you, to be 100% certain, try the port echo function again? In the meantime, I will try to write a simple program which forwards the com port to another one. So basically the same thing as the port echo function in Realterm does but then I will also try to filter the data such that only data is forwarded which meets the requirement: 1x 2x … Dx Ex.

This will take some times since I have no experience with programming COM ports and I have higher priority tasks in the pipeline too :wink: Anyway probably somewhere next week I hope you can test some parts.
Btw do you know how to run a python script? since perhaps that will be the fastest way to develop/test, no problem if you don’t.

If it’s just running a Python script, I can do that! I set myself the goal of learning Python some time ago because I would need it for my current projects, but I move slowly. I programmed in Basic at the time of the Sinclair ZX80, but since nothing, then I have a lot of new concepts to integrate and neurons to unblock. But just launching a script, yes I can ! By the way Python 2.7 is already installed on my machine.


This is just to inform you that I made some tests with a 10 years old DELL laptop running W10 and the result is also negative. The COM port is properly detected by PC-Link, but as soon as I enabled the pc-link mode on my multimeter, error messages are poping up endlessly. I’m not sure it helps to understand the issue, but…


So I finally had time to write the python script and I hope it will work for you. I tested it with the data file you send me and it looks promising. you can download the python script here: we.tl/qrw06uuDMz

The script uses the pyserial library to connect to your com port. If you don’t have this library you can install it by typing “pip install pyserial” (without the quotes) into the windows command prompt. To run the script type “python dvm1200.py -i -o ” into the command prompt where you need to replace by the profilic com port connected to the multimeter and by one of the com ports of the com0com. So for example if COM3 is connected to the multimeter and COM8 and COM9 are my com0com pair I would type: python dvm1200.py -i COM3 -o COM8
Now all the incoming data from COM3 is redirected to COM8. My script doesn’t only redirect, it also does some specific error checking on the incoming data such that only valid data is forwarded to COM8 which will prevent the popup of error messages in the pc-link program.

The best order to connect everything is as follow:

  • connect the multimeter to the pc (don’t enable the PC-LINK mode yet)
  • start my script with the correct input and output port. leave it open in the background.
  • start the PC-LINK software (the version you can download from the velleman website) as administrator and set the corresponding com0com pair port as input. So in my case this would be COM9 since COM8 was used as output in my python script. When the correct COM port is selected press “start”.
  • Enable the multimeter in PC-LINK mode.

Now fingers crossed and everything should work. My python script will print the incoming/forwarded data to the command prompt. Also there is a counter which increases only if data is successfully forwarded.

Dear Sir, I must tell you that it works !!! And I prove it: we.tl/OxXB0eBMIi.

It’s really great what you did. I read the script, for me the Chinese Mandarin is much more comprehensible, but the bottom line is that it does! And you did it! Congratulations and a thousand thanks!