Hi,

although I don't have a chance to test your code, it looks very similar to what I am using.

I can confirm that the DRS4 communication breaks down if the program talking to the DRS4 is closed abruptly or before is has a chance 
to properly execute "delete drs" where it closes the USB connection.

For me if I terminate the program that's using DRS4, the next time I might or might not be able to connect to the DRS4 because I would 
get a magic number or the program would just stop. The DRS4 eval board needs to be restarted via pulling the plug if the orange LED is 
not ON.

I have tried to power down the DRS4 board via software under SL6 linux, but the reality is that the DRS4 eval board is powered directly 
by the 5V USB rail off the computer, and you cannot software control that, you can only suspend the communication of the USB 
port/device.

So I don't have a solution to fix this issue, but my best advice is to change your software such that it calls "delete drs" to 
terminate the USB connection before you close or terminate the program.

Oh and I have not tried running multiple programs at the same time to see if that might be causing the issue as well. The usb library 
might simply error out saying the device is inaccessible because it's being used.

> Hello the DRS4 team,
> 
> I and some of my colleagues are using DRS4 evaluation boards (ver. 3) for the R&D of the Cherenkov Telescope Array project. During 
> our PMT measurements, we have encountered a problem which is probably related to USB connection. In fact, I cannot reproduce this 
> problem with my Linux virtual machine (Scientific Linux 5 64 bit), but other colleagues from three different universities in Japan 
> reported the same problem with their real machines.
> 
> === Short Summary ===
> DRSBoard::SetFrequency occasionally stops
> 
> === Environment ===
> - drs-3.0.0
> - Scientific Linux 5.5 (32 bit)
> - lib-usb-devel-0.1.12-5.1.i386
> 
> === Steps to Reproduce the Problem ===
> 1. Compile the attached file drs_simple.cpp with drs-3.0.0
> 2. Repeat the following command several times from a terminal
> 
> $ drs_simple -0.05 1000 ./outputfilename.dat true 2.
> 
> 3. The above command may stop. In that case, you need to kill the command by Ctrl-C.
> 
> === Comments ===
> - Once the command stops, we cannot run the above command properly.
> - If we unplug and plug the USB cable again, the command can be executed again.
> - It seems that the program stops inside DRSBoard::SetFrequency
> 
> I would very appreciate it if you could give me any advise. If you need further information, please let me know.
> 
> Akira