TWAINDSM.DLL not backward compatible?

[clivew]

I thought the specs said that TWAINDSM.DLL was backward compatible with e.g. TWAIN 1.9 drivers.
I am having a problem talking to a Canon DR-2510C when switching from TWAIN_32.DLL to TWAINDSM.DLL.

When I switch my code to point to TWAINDSM.DLL (ver. 2.2) I see the following in my code:
(FYI: Windows 7 Pro 64-bit)
1. LoadLibrary – succeeds.
2. GetProcAddress for DSM_Enry – succeeds.
3. Create a Parent window and get its handle – succeeds.
3. DG_CONTROL, DAT_PARENT, MSG_OPENDSM – fails

I am not sure if the ConditionCode returned is consistent; but I have seen it come back as 10 (BadValue I believe)
from DG_CONTROL, DAT_STATUS, MSG_GET.

Can anyone shed light on this?

Thanks,

Clive

[clivew]

Turns out it is NOT totally compatible.
TWAIN_32.DLL accepts empty strings for
version.Info
manufacturer
ProductName
ProductFamily

TWAINDSM.DLL does not.

I have not established whether all or only specific strings are required yet.

Took me a lot of wasted hours to track it down, so I hope it helps someone!

Edit: On further testing it seems that only ProductName is required.

Clive

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