National Instruments NI 9411 Operating Instructions And Specifications page 18

Input current
At 5 V 1 mA per channel
At 24 V 4 mA per channel
Input impedance................................ 8.4 k
I/O protection
Input voltage
(channel-to-COM) ...................... 30 V max
Input current  4 mA, internally limited
Input delay time ................................ 500 ns max
MTBF ............................................... 800,319 hours at 25 °C;
Note
at other temperatures or for MIL-HDBK-217F
specifications.
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Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method
Contact NI for Bellcore MTBF specifications
17 NI 9411 Operating Instructions and Specifications