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Digital Logic Compatibility for R Series Multifunction RIO Devices

Updated Feb 23, 2018

Reported In


  • USB-7845
  • USB-7855

Issue Details

What digital logic compatibility do the NI R Series Multifunction RIO Devices have?


Digital logic compatibility varies between R Series cards. The following table summarizes the supported logic levels.
DeviceSupported Logic Levels
USB-78xxR, PXIe-78xxR, PCIe-782xR 3.3 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V
PXI-78xxR, PCI-78xxR, PCIe-781xR,
PCIe-784xR, PCIe-785xR
5 V, 3.3 V (see note below)

USB-78xxR, PXIe-78xxR, and PCIe-782xR devices can receive a maximum input voltage of 3.6 V as described in their specification documentation. These devices have software-selectable logic levels as listed above.

PXI-78xxR, PCI-78xxR, PCIe-781xR, PCIe-784xR, and PCIe-785xR devices are only compatible with 5 V and 3.3 V digital logic levels. These devices can receive signals from 3.3 V or 5 V TTL or CMOS devices. They may also drive signals to 3.3 V or 5 V TTL devices and 3.3 V CMOS devices. They cannot directly drive a signal to a 5 V CMOS device. The Voh of the PXI-78xxR, PCI-78xxR, PCIe-781xR, PCIe-784xR, and PCIe-785xR is not high enough to guarantee a valid logic high at the receiving device, so you must add an external pull-up resistor to 5 V on the digital output line. Please see the user manual for more information.


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