These preference options enable you to determine the I/O types of the instrument tags that become available in the I/O Assignment window. One setting allows you to make all instrument tags be available in the I/O Assignment window regardless of their I/O type. The other setting limits the availability of instrument tags only to those instruments whose I/O type is identical to the I/O type of the current I/O card.
Note that after you effect an I/O assignment and your preference was set to the Same I/O type for tag and I/O card, you can still change the I/O type of the I/O card if you need to do so. The software does not verify the compatibility of a changed I/O type with instrument tags already associated with I/O cards.
To access these preferences, in the Preferences dialog box, in the tree view pane, click 
beside Wiring and then click I/O Assignment.
I/O assignment validation
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Same I/O type for tag and I/O card — Limits the I/O type of the instrument tag to be the same as the I/O type of the I/O card selected in the I/O Assignment window. Note that the software validates I/O type compatibility also upon connection.
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All I/O types — Allows the selection of all instrument tag I/O types in the I/O Assignment window and upon connection.