I have tried other controllers and don't see this effect. We have 5 products and 3 of the 5 are effected in this way. Timothy Knudtson iConnectivity On Aug 23, 2013, at 12:10 PM, Matthew van Eerde <Matthew.van.Eerde@xxxxxxxxxxxxx> wrote: > Does using a different USB controller have any effect? > > From: wdmaudiodev-bounce@xxxxxxxxxxxxx > [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Timothy Knudtson > Sent: Friday, August 23, 2013 11:00 AM > To: wdmaudiodev@xxxxxxxxxxxxx > Subject: [wdmaudiodev] MIDI SYSEX response lost > > Our company is working on MIDI devices that are configured using SYSEX > messages. I am seeing a weird behavior with Windows 7 and Windows 8. I send > 5-10 SYSEX messages to the device and receive the expected responses, then > for the next 20-300 messages the responses do not come back. After sending > those 20-300 SYSEX messages the response start coming in. I have placed a > Beagle (USB logger) on the line and setup USB logging in windows. From what I > see the responses are being sent from the device. The response size of the > SYSEX messages is less than 128 bytes (around 50 bytes on average). I have > tried using the WindowsMM libraries and the KS libraries and they both > exhibit the same behavior. My felling is that the issue lies in the > USBAudio.sys driver. > > This device works on Windows XP, Mac, and iOS. I have not tested on any other > platform. > > Any help would be appreciated. Thank you. > > Timothy Knudtson > iConnectivity > > > >