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saraff-9EB1047A4BEB4cef8506B29BA325BD5A / Saraff.Twain.NET

Saraff.Twain.NET is the skillful scanning component which allows you to control work of flatbed scanner, web and digital camera and any other TWAIN device from .NET environment. You can use this library in your programs written in any programming languages compatible with .NET technology.
GNU General Public License v3.0
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Saraff.Twain.Sample2 freezes after second scan #37

Closed Nick-Burger closed 5 years ago

Nick-Burger commented 5 years ago

I have a HP OfficeJet Pro 6970 Printer/Scanner and setup the first scan to 100dpi/Grey/Native. Using the ADF with two pages both pages where scanned perfectly as expected. As I modified one single line the duplex property is set to false and only one side of the pages is scanned.

_twain32.Capabilities.DuplexEnabled.Set(false);

Then I place another two pages in the ADF and chage to 100dpi/RGB/Native. This two pages where also scanned as expected. But the AcquireCompleted event is never fired. If I try to change either DPI or any other capability, the sample program freezes and the call set the new value never returns.

ThanX for your help! Nick

saraff-9EB1047A4BEB4cef8506B29BA325BD5A commented 5 years ago

Hello, @Nick-Burger Try check expression e.Exception.ReturnCode==TwRC.Cancel in a _twain32_AcquireError method.

Nick-Burger commented 5 years ago

Thank you for your quick response. In _twain32_AcquireError e.Exception.ReturnCode never gets the value TwRC.Cancel.

saraff-9EB1047A4BEB4cef8506B29BA325BD5A commented 5 years ago

Hello, @Nick-Burger Did was a _twain32_AcquireError method invoked? If yes, that what values has the properties e.Exception.ReturnCode and e.Exception.ConditionCode?

Nick-Burger commented 5 years ago

AcquireError event is not fired. I can get around the Problem by keeping the datasource closed. When I open the datasource right before _twain32.Acquire and close it on AcquireCompleted I can repeat these steps how ofte I want. But keeping the datasource open like in the sample2 project will only work for the first call to _twain32.acquire. After the second call it will freeze after the last scanned page.

saraff-9EB1047A4BEB4cef8506B29BA325BD5A commented 5 years ago

Hello, @Nick-Burger Highly likely, that this issue related with a datasource of your scanner (it can be not fully compliant with a twain specification). You can try send question to a hp customer service.