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PXIe-4300 Terminal Block Effect on Input Impedance



Hardware: Multifunction DAQ (MIO)>>SC Express, Multifunction DAQ (MIO)>>SC Express>>PXIe-4300, Multifunction DAQ (MIO)>>SC Express>>PXIe-4300

Problem:
I am using the NI PXIe-4300 with the TB-4300 or the TB-4300B, what is my input impedance?

Solution:
According to the the PXIe-4300 Specifications Manual, the input impedance will be different depending on whether the device is on or off.  This is due to protection and signal conditioning circuitry that is only active when the device is on. 

When on, the NI PXIe-4300 has over 1 GΩ input impedance between AI+ and COM, and between AI- and COM. As shown in Figure 1 below.


Figure 1: NI PXIe-4300 Input Impedance with no Terminal Block

The NI TB-4300 is a non attenuating feed-through terminal block. It has no effect on the input impedance of the device, as shown in Figure 2 below.


Figure 2: NI PXIe-4300 Input Impedance with TB-4300 Terminal Block

The NI TB-4300B is an attenuating terminal that has a 1.2 MΩ impedance between the AI+ and AI- pins as shown in the Figure 3 below. This terminal block has no effect on the impedance of the NI PXIe-4300 impedance between AI+ and COM or AI- and COM.


Figure 3: NI PXIe-4300 Input Impedance with TB-4300B Terminal Block



Related Links:
Product Manual: NI PXIe-4300 and TB-4300/B/C User Guide and Terminal Block Specifications
KnowledgeBase 5BDGCRHL: PXIe-4300 300V Interchannel Isolation Specifications Explained
Product Manual:  NI PXIe-4300 Specifications Manual

Attachments:





Report Date: 02/19/2013
Last Updated: 10/06/2017
Document ID: 66IFB1HJ

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