USB Connection problem - solutions

USB Connection problem - solutions, a forum discussion on Cleverscope Mixed Signal USB Oscilloscopes. Join us for more discussions on USB Connection problem - solutions on our Interface issues forum.

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30 Nov 2013
Posts: 5

I have experienced a lot of USB connection problems over the years with my CS328 and have recently discovered three solutions that I would like to share with other users:

1) Sometimes it takes a *long* time to make the initial connection (after you start the CS app and initiate a trigger). The connection problem dialog mentions that it can take up to 10 seconds; I often experience 20 second delays. I used to confuse that delay with it not working; after about 15 seconds I would give up and try to restart the CS app.

2) The delay times seems to be related to the number of distinct FTDI devices that have ever been plugged into your computer. I use FTDI serial devices for connecting to many kinds of hardware gadgets. When Windows sees an instance of an FTDI device, it assigns a COM port number for it. Over time, there can be a lot of them (40 in my case). That seems to affect the CS attach time. After I cleaned out a lot of stale COM ports the CS attach time improved dramatically. (To remove unused ports, Google for "Windows delete unused com ports").

3) Recently, even after unplugging all other USB devices, shutting down other apps, restarting the CS app, and even rebooting the computer, the CS app failed to attach the USB CS328. I finally fixed it by going into device manager and disabling/re-enabling the Cleverscope CS328 MSO device.


2 Dec 2013
Posts: 481

Hello WMB,
Thanks for sharing this with us. We had not understood that there might have been so many FTDI COM ports hanging around.

Now the CS328 was last produced in 2006, and since then we have been making the CS328A, which uses the Cypress 68013A, and our own driver. So we are hopeful that the issue of other COM ports should no longer affect things.

Another thing you might like to check for is to ensure that the Settings/Choose Acquirer and Set Connection .. has the Interface source as USB. If the source is Ethernet, the application needs to wait for the connection timeout before it tries the CS328A driver for a connection, and then that times out, before trying the CS328 classic FTDI driver for a connection. All of that can add up to quite a wait.

We hope otherwise, the Cleverscope has given you good service.

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