In the NI-9350 getting started guide, a number of different input/output configurations are specified. As most emergency stop (E-stop) buttons are normally closed switches (NC), the "Single Input with Test Pulse Connection" and "Dual Input with Test Pulse Connection" configurations should be used, these are both shown below.
Single Input with Test Pulse Connection
This configuration should be used for an E-stop with one NC connection.
Dual Input with Test Pulse Connection
This configuration should be used with E-stops that have dual NC connections.
Note: Use one of the following pairs for dual switches: DI0 and DI1, DI2 and DI3, DI4 and DI5, or DI6 and DI7.