USB Selective Suspend under Win7

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willem
Posts: 17
Joined: Tue Oct 25, 2005 3:09 pm
Location: Netherlands

USB Selective Suspend under Win7

Post by willem »

Dear readers,

We're facing some unwanted behaviour of our IO control system based on the IOW56 module.
The system is used for controlling long term experiments (hours...days) and we're using both "simple" TTL I/O" and the SPI features on the IOW56.
One of our users complain about missing I/O actions on a quite unregular base, "as if the USB connection was lost for a moment"......
Whenever I'm checking/testing, the problem doesn't appear...., this make it extreme hard to find out what is going on.

Question:
Win7 has quite some power-save options. One of them is the "USB selective suspend" (advance settings / USB).
Also in the BIOS there seem to be some USB power related options.
Could communiction to the IOW-56 module be corrupted by the USB selective suspend mechanism??

For your information, IOW56 Vcc supply comes just and only from the USB port, supply for additional hardware comes from a sepate source.

Regards,

Willem

Guido Körber
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Re: USB Selective Suspend under Win7

Post by Guido Körber »

The selective suspend should not become active when there is traffic with a device.

Does the configuration include an external hub? Some hubs are of so low quality that data transfers can get lost, usually due to bad power supply.

willem
Posts: 17
Joined: Tue Oct 25, 2005 3:09 pm
Location: Netherlands

Re: USB Selective Suspend under Win7

Post by willem »

Hallo Guido,
I understand that whenever there is USB traffic the USB suspend mode will not be active. However within our experiment setup with the IOW56 involved for the actual IO, it is quite common that there is no I/O (hence USB commands to/from IOW56) for several minutes, hours and sometimes even days.......
During this time our software (wich included the IO tasks for the IOW56) is still running and quite busy by capturing video and displaying al kind of info on the screen, this process is going on fine.

Could it be that the PC system indeed get into some USB suspend mode (after some time) making the IOW56 behaviour unregular.
Our user stated it seems the system (IOW56) missed some I/O instruction before getting functioning fine again....

Regards,

Willem

willem
Posts: 17
Joined: Tue Oct 25, 2005 3:09 pm
Location: Netherlands

Re: USB Selective Suspend under Win7

Post by willem »

... sorry forgot about hubs...

No we are aware of hub problems and even don't use (these times quite common) USB connection on the monitor.
IOW56 is always connected directly to the USB port on the PC's main board (back side of PC).

Regards,
Willem

Guido Körber
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Joined: Tue Nov 25, 2003 10:25 pm
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Re: USB Selective Suspend under Win7

Post by Guido Körber »

That makes it sound like there actually may be a problem with the bus getting partially suspended. One way to avoid this without requiring the user to specifically set up the system would be to continually send some commands to the IO-Warrior.

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