National Instruments NI 7831R User Manual

Also see for NI 7831R: User manual User manual User manual User manual

Contents

National Instruments NI 7831R User Manual Manual pdf 24 page image

Chapter 2 Hardware Overview of the NI 7831R© National Instruments Corporation 2-5 NI 7831R User ManualConnecting Analog Input SignalsThe AI signals for the NI 7831R are AI<0..7>+, AI<0..7>–, AIGND, andAISENSE. The AI<0..7>+ and AI<0..7>– signals are connected to theeight AI channels of the NI 7831R. For all input modes, the AI<0..7>+signals are connected to the positive input of the instrumentation amplifieron each channel. The signal connected to the negative input of theinstrumentation amplifier depends on how you configure the input mode ofthe device.In differential input mode, signals connected to AI<0..7>– are routed to thenegative input of the instrumentation amplifier for each channel. In RSEinput mode, the negative input of the instrumentation amplifier for eachchannel is internally connected to AIGND. In NRSE input mode, theAISENSE signal is connected internally to the negative input of theinstrumentation amplifier for each channel. In DIFF and RSE input modes,AISENSE is not used.Caution Exceeding the differential and common-mode input ranges distorts the inputsignals. Exceeding the maximum input voltage rating can damage the NI 7831R and thecomputer. NI is not liable for any damage resulting from such signal connections. Themaximum input voltage ratings are listed in Table B-2, NI 7831R I/O Signal Summary.AIGND is a common AI signal that is routed directly to the ground tie pointon the NI 7831R. You can use this signal for a general analog ground tiepoint to the NI 7831R if necessary.Connection of AI signals to the NI 7831R depends on the input mode of theAI channels you are using and the type of input signal source. Withdifferent input modes, you can use the instrumentation amplifier indifferent ways. Figure 2-4 shows a diagram of the NI 7831Rinstrumentation amplifier.