DAT_PENDINGXFERS / MSG_ENDXFER slow

[jov]

Hi all TWAIN gurus 🙂

We are noticing that calls with DAT_PENDINGXFERS / MSG_ENDXFER are very slow (3.5 to 4 seconds) and that this is slowing down imagetransfer from scanner to PC.

Can anyone shed some light on possible causes for this?

Thx, Joep

[Kaij]

Joep,

That sounds unusual. But to find a root course you should share more details as used DS, used programming environment etc.

Best regards,
Kaij

http://www.jse.de

[jov]

OK, let me explain some more indeed. After starting a scan job with a Canon DR-4010C, the first few pages are scanned with normal speed, then scanning slows down to 1 page every 3 to 4 seconds. I can track this down to the DAT_PENDINGXFERS/MSG_ENDXFER call to DSMENTRYPROC. It takes 3 to 4 seconds for the call to return. I can reproduce the problem on an old, slow computer, but his computer isn’t that slow. We have more than 100 other users with the same scanner that do not experience this problem.

I have timed a lot of steps in our app, like transferring the image from the source to the application or writing the image to disk, but the lag definitely is in the before mentioned call in the TWAIN driver. I just am wondering what could be slowing down this call. Since the 3 to 4 seconds are not taking place in our app, it is less likely that our app is the cause – but is that so? Which external factors/programs could seriously slow down the TWAIN driver? Is it something bufferish? Any ideas?

[Author]

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