[wdmaudiodev] Re: MIDI SYSEX response lost

  • From: Timothy Knudtson <tknudtson@xxxxxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 23 Aug 2013 13:05:12 -0600

There is a single endpoint that provides multiple ports. This is a class 
compliant MIDI device.

Devices with more ports do not drop earlier. But it appears that they take 
longer to recover (300 Message for 16 port device vs 64 for 4 port device).

The amount of data it takes to recover varies based on device. I don't know the 
exact amount but it is between 20-300 messages of around 55 bytes each.  It is 
possibly a fixed amounts of bytes but I don't know what that is.

It is not a fixed time because you can close the program after sending a few 
SYSEX Messages, then wait a few minutes and restart the program and the 
responses will still not return.  Once the response do return it they will 
always return until you disconnect and reconnect the USB cable.

Timothy Knudtson
Software Engineer
iConnectivity
403.536.8274 | iConnectivity.com





On Aug 23, 2013, at 12:45 PM, Clemens Ladisch <clemens@xxxxxxxxxx> wrote:

> Timothy Knudtson wrote:
>> I don't know if this is applicable but the devices that are effected provide 
>> more than 1 MIDI port per USB Port (12, 4, and 16).
> 
> How?  Virtual cables, multiple endpoints per interface, and/or multiple 
> interfaces?
> 
> Do devices with more ports drop data earlier?
> 
> How long does it take until received messages come in again?
> Might this be a fixed amount of time or a fixed amount of bytes?
> 
> 
> Regards,
> Clemens
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