# How to check for corrupt DMAPs before scanning BeadChips using the iScan

DMAP files may transfer incorrectly to the network during downloading and file integrity can be compromised. The iScan can be configured to check the DMAP file integrity at the start of each scan.

**Note:** Enabling this feature increases the amount of time before the iScan begins performing the scan.

**To verify DMAP file integrity**:

1. From the menu in the upper left corner of the screen, select **Tools** > **Options**.\
   ![iScan Menu: Select Tools > Options](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-1d1a1d8022968a0373e2d67db2114e74a7d019d8%2Fimage1.jpg?alt=media\&token=b665bd35-1434-457d-9e14-54146674768a)
2. In the Options dialog box, select the **General** tab.
3. In the Processing section, select the **Enable Corrupt DMAP Check** checkbox, and then select **OK**.\
   ![iScan General Tab: Select](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-7e11b8c3d37d453262151f66271bd6bab7f5f477%2Fimage2.jpg?alt=media\&token=3f72118d-35f4-4838-bb2a-55051b73f8f6)

For additional information, see the [iScan System Product Documentation](https://support.illumina.com/downloads/iscan-system-product-documentation.html).

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #3861), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000003861%20-%20Microarray%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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