New tool for capturing data in windows

So most serial terminal applications were designed for communicating via printable ascii characters, using the high end codes for control codes. We previously recommended using RealTerm to inspect the serial data (and capture it) in windows because it seemed to be geared towards this type of application. However, most of our users (and ourselves) have found RealTerm to by quite unstable.

So we wrote a quick application you can run in windows to capture data from the TrueRNG. It’s not fancy, it runs in a console window, but it works.

Here is a link to


Extract the zip file to somewhere like c:\random

It is a console application so you will need to run it in a dos window. In windows 7 hit the start menu, then type in “cmd” you will see the dos window application.

You should see a prompt that looks like “C:\>”, Change directory to that directory “cd c:\random”

Then type in “rngcapture” with no arguments and you will see something like below

TrueRNG Serial Port Capture Tool v1.0

rngcapture [port number] [filename] [number of bytes to read]

Searching for available COM ports…
COM43 – – USB\VID_04D8&PID_F5FE\6&8959E51&0&4
Found 1 port


This is showing the arguments and a list of com ports. For me the TrueRNG device shows up as COM43. So to capture a 1 megabyte file I type

“rngcapture 43 randomdata.bin 1000000”

Which means use com 43, save the data in randomdata.bin and capture 1000000 bytes

and the output looks something like:


C:\random>rngcapture 43 randomdata.bin 1000000
Opening serial port \\.\COM43…OK
Capturing data…
998400/1000000 47.25k/s
Capture Done
Closing serial port…OK


We hope this helps those of you who are battling with RealTerm crashes.


2 comments on “New tool for capturing data in windows

    • on said:

      The driver is linked on the bottom of product page here in the downloads section. And here is a direct link to the inf file. You should be able to unzip the file to a temp directory, go to device manager right click and update driver, then point to the inf and you should have a com port.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.