Solution:

1. PCI-1756 digital input accept upto 50Vdc, input range of low level is 0 to 3 V; the range of high level is 10 to 50 V. 2. With fixed protection circuit inside PCI-1756, The digital input channel wil have different input current; e.g., input voltage 10V will have input current 1.7mA 3. In high voltage input condition, one thing we must concern is the heat dispense of PCI-1756. In some thermal sensitive instrument, it may cause the instrument collect fail data or affect the instrument.