DISABLEDS returns TWCC_CAPUNSUPPORTED?

[hutdone23]

I believe I’m seeing a Twain Driver bug in the Epson GT-S50 scanner in my Twain application, so I removed my code from the problem and can demonstrate the issue using Twacker alone. Here’s the steps to replicate the issue:

1.) Run Twack_32.exe

2.) File->Select Source…

3.) Select the Epson GT-S50, press the Select button

4.) File->Setup…

5.) Close the Scanner’s UI.

The call to the triplet DG_CONTROL/DAT_USERINTERFACE/MSG_DISABLEDS returns TWRC_FAILURE where the condition code TWCC_CAPUNSUPPORTED.

The call is made in the Twacker source code, DCA_GLUE.c, line 807, in TWDisableDS(). Using the Kodak i40 scanner for example I don’t see this problem following the same steps.

It seems very wrong that calling MSG_DISABLEDS would return unsupported capability, any thoughts?

[peterp]

The TWAIN spec is very clear on the allowed return codes during a failure of the MSG_DISABLEDS operation, and TWCC_CAPUNSUPPORTED is not one of them.

The allowed return codes are:

TWCC_BADDEST
TWCC_SEQERROR

You should only get TWCC_CAPUNSUPPORTED if you are trying to get or set a capability and there is a problem.

[hutdone23]

@peterp wrote:

The TWAIN spec is very clear on the allowed return codes during a failure of the MSG_DISABLEDS operation, and TWCC_CAPUNSUPPORTED is not one of them.

The allowed return codes are:

TWCC_BADDEST
TWCC_SEQERROR

You should only get TWCC_CAPUNSUPPORTED if you are trying to get or set a capability and there is a problem.

peterp, I filed an incident report with Epson, not sure if it will make it to their Twain driver engineers, but hopefully it can be addressed.

Thanks

[hutdone23]

In case anyone is interested, this is a driver bug and will be released in a future update by Epson.

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