Connecting a Single-Ended Device to the NI 9411

[Andrey_Dmitriev]

I have some troubles with electrical noise (sometimes signal detected in absence of the real signal) while using NI 9411 with 24V single - ended device (which have own power supply).

According to cover sheet I can connect Diff/Single Ended +/-5 to 24V signal to this module:

From the user manual:

Already put pull-down resistor between DIa and COM, no effects, still some sporadic peaks received.

My question is about DIb - this input just "in the air" and not connected in this mode as shown above. But this is differential input. Should I connect DIb to the COM as well or keep unconnected?:

[santo_13]

You can leave DIb floating.