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?:
